26
OONTRIBUTIONS TO THE HISTORY OF THE
·RorrIFERA, OR WIIEEL ANIMALCULES.*
BY PliILIP FIENRY GOSSE)
F.~.S.
l~
T:fIE C'BOWlf ANIM.A.taULE
(St8!phal{~O(Jflros B~(J}~}~ornii).
LITTLE mora than a dOZien years ago" being-then resident,
A
., . ill London, I became a great f:requenter of all the accessible collectiollS of water in "the vicinity of the metropolis, I
had just purchased a mioroscope, and, loqking with ignorant but
interested curiosity a~~o~e dr~ps ~fwate~frolm a neiglibouring
p~()l)wa,s,cha'llledwit:hthe, vaN.ealo,msand
sprigl1tlymotions
rphe 1"88 ul t
.:~e~e~illatio~ t~ studr811cl depict these-
~ilt~r~~~hl~t:Vc:l~0.~ispiClrtingthere.
w~S\ ..••.......••...'.••. ", '"
theo,eaA~i1tr~"~~"fll~{:r~t~at~er'~iat~hattiJ:ne incltl~edunder a
fSinglegr0tiJ>'~E.~ ,:hi~h~Q€l:~~e~~rn~~~!~~ .• or'~ne,dt1p tQ the
soientific warla ,b;llt?r'()ft!}~vsl€HtEnre!E1~@'~g',~lr'~;e'Flin,;~).}~isnlag-
l1ificentwork, Die 111flbG$,~,~~8fkiel/~e7t{J~.; ~i~o,
"e~i~~~,s1een
'sadly pulled to p,ieCeSf} like,S blook . efg~~it~,~I~whieh the
constituent sile:xa:nCl feldspa:P' and. taiea lie seaii'ere,d in disintegrated granules) the great class Infusoria, so compact and firnl
as it appeared in the folio of the eminent Prussian microscop:ist,
has dissolved under the storms of scientific controversy. One
runs a,vay with the Rotatoricf.J, another with the Desm1:clecc, a
third with the D'iato1nacece: the Jlhizopoda get piekil1gs j the
Annelida
in a claim; and the remainder is so nibbled at,
to huddle away the few. slleets of delicate
hands, and hid
,THE CROwN ANIMALCULE,
27
aud deliueatioJ1 of these tiny creatures became the absorbing
occupation of my entire leisure. So elegant are their outlines,
so brilliaJ1tly transluceut their te:x:tu~'e) so complex and
yet so patent their orgapization) so curious their locomotive wheels) .sq unique their apparatus for mastication) so
gra,ceful) .so vigorous) so fleet) and so marked with apparent in.
teUigence their movements) so various their forms and types of
stl'lwtlp'e) so readily attainable for study in almost every locality,
-and at all seasons of the year: that) as fad afterfact and detail
after detail of organization and habit revealed itself to me) I
often wondered that scaroely allY one seemed to know anything
about thew b~YOl1d what might be picked up fJ:Qm turning ovet
the~~rE)+!-'P~1'g atjhe §'Qir~e~ of the MicroscopioaJ;
opf 1 ' F J " t i p l l pf hi§. Mterpl'csS aPc1 the copies
of his
." . .•. . j ••' .; : " .
.~]:'~h~~.pl.J,lJli~h~~.
I have said tha,tt .·.llf we pE stllc1~l1+a,~~.jJ1@ifa~li1iarwijih WQsji
of the accessible coIlectjol1§ of wnterjllallc1a11Qllnc1.I!.ol'J,90P;
It is one recommendation of tlw class:R.q'lJ*li'1ilRAa,SI:l"l~Qbject of
research) that the species are so easily prQcurable) even to a
resident in great cities. A moderate walk sufficed to pnt me in
possession of some or other of tho hunched aucl twenty species
that I know to be British) all of which) with the exception of a
dozen or so) I have found immediately around London..
Some' of these waters Were private. My very first essay wall
on a pond in the grounds of Mr. Samuel Bergel') at Claptoll i
where the white lily was sitting like a queen amidst hel'l'ouncl
green leaves) on the still surface. The large E'llchltmis clilatc~ta
swimming at large) several kinds of Salp7:na grubbing among
the Nitella leaves) the pretty Mastigoccrcq, CM'1,nata) with its rat.
tail and its singular llnsymmetriqal (lQl1sa,l kl3eJ) a,llcl the Cll1'iotls
.Ac#nwru,s Nepl~~fLh~s) l1el'lJarlqj,oll'l fQp jt~l3J!,'tr(3~e dOVI3IQpll1en~
in length) with other j:q,q1'(;) fall1i1i~R.~l.JJ;.€l~~1i'.~WI,HJdl'lg;l'JJ;yso.~qb.
here. :J!'l'QW ~ 11y.§!3r~qitjl'J,.~h.!3$'!'9}l~c1'~i.lilfiM!1);~:#-\-l~l'@cl~qsliIlg,
a,t q./.li~~fil1fxv!r,JIl . . ~@J1tl ..t.~~ell./~~frJ/~Cf!tq,~if"':P ewspecies)
JJ'~~~'r;t~lqt?'iq,gVf~iJ,ili~).1?lvilocli~tq,1'0
rernl1l'kable for the rosy
hue with which its trallsparent tissues are tinged) Notommcdct
l?etrornyzon, with its oonspicuous ruby eye) and N. pn?'Ctsitn)
eating out the interiol' of the majestic spheres of Volvox globa.tor,
A tallk in the garqen of Mr. B. Edwards) at Sborec1itch, whlCh)
thouO'h in the midst of brick and mortar) has beon celebrated
for the treasures which it has yielded to microscopists for more
than a century) has yielded me) among 'many other' things. of
interest) the fine Botifcl' ~1W.C1'U1'US) Philoclina aculeatct, so Sll1gularly studded with curved prickles like those of 11 rose-bush,
nuda new species of the very interesting genus) Oallidina. A
f3mall reservoir in my own .gardon) an~l even a mere earthenware
pau) filled with water and a,llowecl to stand in the garden fors0111;o
30
POPULAR SCIENCE REVIEW.
the rare and noble Stephanoce),o8 Eichhomii. It was not till
after years of searoh that I disoovered this; but) in A.pril)
1850) it occurred in considerable numbers adhering to the
minutelypeotinate leaves of M1Jr1~oph1fllt~m) pieces ofwhioh were
floating on the surface, and were washed on shore by the little
wavelets that the breeze threw up.
The next year) at the same season, I again obtained it at the
same spot; but in less abundance. A year or two afterwards I
. tried again; but the pond had been cleaned out) the M1Jriophyllum had been carefully scra,ped to the shore and carted
away, and not a Stephanocero8 have I been able to find there
from that day forward. I learn, however) that it has been
taken in a pool at Highgate) and my kind friend) Mr. W. P.
Bodkin) who furnishes me with the information) has promised
to be on the look-out, hi order to supply me with specimens.
'1'0 the history of this fine species I now address myself.
Stephanocm'os and F'losculcm'ia, are the most abnormal genera
of the class ROTIURA. They are very closely a1lied -inter' se;
but differ importantly from all other forms. I associate them
into a family, marked by the following charaoters.
F.AMILY FLOSOUL.ARI.ADlE, OR THE PLOWER
.ANIM.ALOULES.
Animal free in infancy, permanently fixed in adult age,
undergoing oonsiderable ohange in form after birth, inhabiting
a gelatinous tube whioh is excreted from the skin. Front
procluced into five lobes, beset with long ciliary setffi, or bristlelike filaments. Jaws seated far down in the abdominal oavity,
not inclosed.in a muscular bulb (mastttm). Foot long) wrinkled
transversely) neither telescopio nor retractile,
GENUS STEPH.ANOCEROS (EITItENnERG).
Frontal lobes long, slender) erect, convergent; oiliary setre
set around them in whorls. Jaws each of three teeth conneoted by a web.
'1'here is but one well-established speoios) viz., S. Eichhorllii
(Eh1'enberg). (See pI. iii.) This exquisitely elegant creaturo
reaches the length of one-fifteenth of an inch, I1n(l is therefore
distinctly visible to the unassisted eye. Ehrenberg can have
seen only small speoimens) as he gives one-third of a line as
its uHimatulll-one-thirty-sixth of an inoh) and Leyclig nltlnes
half a line) or one-twellty-fourth of an ineh; but I have seen
several individuals of the dimensions I have named. The fivo
10beEl' which take the form of the petals of a flower in F'loscular'ia, are here produoed into long slencler inoul'ved arms and
the long setffi are arranged in vertioils or whorls. They 'have
~lOt the Jel1gth of those in 1i'lQ8(yula7'~:cb,.but are still muoh 1011g'cr
THE CROWN
ANIMALCULE.
31
than Ehrellberg has figured them. I have traced them to a
length equal to two-thirds of the greatest diameter of the bocly.*
The points, however, run out to an extreme tenuity, aud cau
only be perceived by the aid of delicate manipulation of the
miorosoope. 'fhe :five arms rise erect from the front, and con.
verge to a rounded point after bulging outward, so as to present
the figure ?fa tall crown or mitre (whenc~ the generic namo);
but the pomts do not actually meet. It IS rare to see a specimen with the arms spread) as Pritohard has figured (after
Ehrenberg) ; I have onoe seen it in this oondition; but I am
persuacled that it is a mark of weakness or disease.
The front, at the base of the arms) forms a broad head,
whioh is separated by a sort of neck from the body. '1'his
neok consists of two thickened collars} procluoed by deep
annular infoldings of the skin. The body is irregularly cylindrioal, or nearly so; bnt is generally swollen out in various
parts by the full viscera, and the cleveloping eggs. '1'he dors!LI
side is the mOl'e swelling, and shows more distinotly the somcwhat abrupt attenuation into the long and slender foot.t At
its junction with the body, the foot is twice or thrioe the
diameter to whioh it diminishes at its lower extremity, whore
it is permanently attached to some foreign olJject, such as the
leaf or stem of some submerged water-plant. 'rhroughont its
length this organ is much and irreguh1l'ly wrinkled; it is
capable of some degree of contraction, but it cannot be
rctraoted within the body; it never shows any trace of
those telescopio false joints which are so oonspicuous in the
Philodinaclce.
Tm: OAsE.---The body is enoased in a gelatinous envelope
(pI. iii.), the general form of which is sub-oylindrical; but
the outline is thrown into irregular transverse folds, apparently through sinkiu'g from its own weight.. It is not a thin
tube, as represented by Ehrenberg, with a roomy oavity, within
which the animal lives, as MeUeer·ta does; but is manifestly a
thiok aud solid (if suoh a term is not a misnomer as applied to
such a material) mass of gelatinous substance, with the exception of the space aotually occupied by the body ofthe animal.
1!-'rom observations made i.1pOn the enveloping Of1se, on occasioIls
in which, for some r<:jason or other, the animal voluntarily forsook it, it was apparent to me, that there was no organic connexion between the animal and its oase, after the latter was
once formed. The cavity left was nearly of the same form and
dimensions as the body and foot, showing that it had beon
»« Leydig makes t1~em ,equal to tl~o full. diameter of the bo~ly,
,
.Leydig's ficrure (m SlOb. and Koll. Zeltschr" July, 1854) lS,both m outlme
and in anatomi~al details, too diagram-like for life,
t
28
POPULAR SC1ENCE REVIEW.
time, have been very prodnctive of g~od thing~. In ~he latter
I have taken the prettylittle house-bUllder, MBlwe1,.tc61'wgBns, on
the finely-cut leaves of the water-crowfoot, as we!l. as th.e s~ill
more elegant Floscula1,ic6 omata, and the exqUlsIte LtJn1~'tas
cBratophylU; and, among the sediment, the long-le&,ged Dt~W­
chC!J1'is IJOCillUl1'/;, the thick-necked Notommatc6 collarts, the tIllY
but active Diglenc6 catellinc6, munching the half-decayec~ leaves
and dropping its large eggs here and there, and the .smgular
creature which I have described under the name of D1,glenc6 (?).
bb'aphis.
Wayside ponds I found productive: There is Ol~e, near the
turnpike-gate at Lower Olapton, whIch I often VIsIted, an.d
always with encouraging success. Among other te~1ants, It
contained Euchlanis l1ma, that form with the shell so Sll1gularly
hollowed in front as to give it the shape of a crescent; the
jumping Polya1'thrc6 platyptem, with its t:velve j~inte~ spears;
several species of Brachion't6s, and an mterestIllg httle new
genus, which I have called P01npholyw. A pond at Tottenhamgreen, well stocked with the Lemnc6 polyrhiza, or many-rooted
duckweed, has given me some prizes. The first phial of ,;ater
I carried home fromthis pool proved veryturbid when exammod,
and appeared to contain no animal life; but, after standing a
week OJ.' two, it became clo:1r, and was found to be densely
swarmingwiththefine Brachionils pC6ZC6, and another specieswhich
I have namedB. angulm·is. A broad pond in front of Forest
School, at Walthamstow, has always been very rich in ROTIFER.A..
Thence I first obtained that large and brilliantly translucent
species, J1splanchnc" Br·ightwelZii, so singular in its structure and
economy, which first made known to us the difference betwecn
the males and the females in this class of animals. Here, too,
I found the elegant CErYistes CJ'ystallimls living in its pellucid
tube affixed to the herbage; BrachionilS amphicc1'os, interesting for the clearness with whioh it has allowed me to
understand some difficult points of' structl1l'e; the noble B.
c{o1'cas, a new species with very long anterior curving spinGs ;
and, swimming at large in the open wator, tho crystallino
Synchcett;(, pcetinc6tc", and the pretty little A1t1WCl?W, incapable of
rest, because destitute of a foot. Hampstead Heath has ahvflYs
been a favourite resort with microscopists. A pond whore
horses are watered, and another just behind the Castlo inn, m'o
very produotive of species; but tiny hollows on the Heath. itsolf,
many of them scarcely a yarcl in diameter, Imod with !1 roc1brown water strongly impregnated with iroll, and complotoly
driedl1]J in hot weather, are unusually rich. In theso, among
:t;lany vegetable forms of much l)eauty [mc1 illtcrosi" I took tho
httle Stephanops, with its arched helmet; the O(Jnoc1l'ao.~ 1wluna',
forming' spherical groups united by the foet; and an interesting
THE CROWN .A.NIMALCULE.
29
new ~orm, which I .have named SacCi~l't6S vi?·iclis. Ponds at
Barkmg, ~t Greenw~ch, at Battersea, ancl other localities, have
also contrIbuted theIr quota to my observations.
. Eve~ dykes and ditches are not to be despised. A small
~Itch .m a fi~lcl at Sha?klewe~ yielded me the lovely, but
I ather .sluggIsl~, Ptm'odmc" pCdtnc6, and the curious T1'icwth1'C6
1n7~sta,c'/;nc6~ whICh leaps yivaciously hither ancl thither, by
means of I~S th~ee long brIstles,-both somewhat rare species.
An?ther ?Itch m Pm's~n's field, Stoke Newington, through
whIch a tmy stream trICkles, procl~ced Noteus qnaclrie01'nis, a
fine, and by no ~eans comIl;10n speCIes. In a dyke at the Islo
of ~ogs, I obtamed Hydattna senta, that transparent spocios
wlnch. E~renberg selected as his standard in describing the
orgamzatlOll of .the class. Ditches at Stratforcl gave me
Ohretonot'll.s hystnw,with Sccl1'idi'l6?n longicauclmn, and Notorn1~wtC6 longUJeta, both remarkable for extraordinary longitude of
lnnb, j a?-cl an extre~nely eurious forn;, very abnormal, as yet
l.111d.esCJ;'1bed, but wlnoh I have called m MS. Oochleare. Then,
agam, m, a dyke at Maiclenhead-~houghthis ~s rather beyond
~ :alk fI,om L.ondon-I found D'lylena [j'/'cmclts,. a very imposm b spec.lOs, hIghly predatory, and furmshed WIth remarlmblo
toothed Jaws; and a new andune species of Salpina -So 'JlW~~'cw(L:tth~, (k[8.). The ~'eservoirs at Oharing Oross, though not
11ch III speCIes, have YlOlded me some of the free-swimming
forms, as Synchcetc6 and Anunec6; and among the conferva.that
grows al~ng the stone-work of the margins, Polyarthm and
PW'C16lc6n:6 forficulc~, a rather good thing.
. OollectlO?-s of w~ter of higher pretensions, such as the lakes
~n the publIc or prIvate parks and pleasure-grounds have not
m ger~eral been more proliuc in yield than these hum.'bler pools
I1nd dItches. Yet these are the suitable places to search for
tho~e forms-in general of great beauty, and remarkable for
then' crystal clearness-which seldom or never rest but are
ever whirling with arrowy fleetness through the wat~r. Such
3;1'0 th.e SynchcetcB, which I have taken in some numbers in that
1me plOce of water known as the Black Sea, on Walldsworth
O~~mon, all~ the A.1~it1'CBce, mostly containing small, but very
brIllIant SpOCIOS, wInch are I1bundant in the lake in Kew
Garc1ens.
TJ:e Serpentine has yieldec1 ~e, besides these,
.AsjJlC&Jwhna jJrwclontc6; I1nd I have taken thIS, together with
NOto11111Wttt elcw-nlaic6, a very une thing, in the water in Regent's
Park. l!'l'om the lake in Richmond Park, I have obtainec1
Stephcl1lo).Js 1ni6tiei6s, Phi.lacrinc" m8galotl'ochc", anc1 some species
of Batt~ll11S, together WIth some of the stationary and tubedwelling kinds, as Flos(mlc61'1~a and McUc8rtC6, anc1 the fine
predatory Dl:r/lcnn f01·cipata. Finally, the water in front of
:ji:~nsington Palaoe proclucec1 me the grElatest treasure of all,
32
POPULAR SCIENCE REVIEW.
modelled upon these. During inhabitation the upper margin of
the case is turned inwards; and when the animal suddenly and
strongly contracts itself, the top ofthe case is somewhat drawn
in after it. But this is not the I'esult, as has been stated, of any
adhesion of the margin to the animal, but simply that of the
action of the water rushing into the vacuum suddenly produced
by the downward retraction of the boay, and carrying in with
it the soft and flexible margin of the case.
The substance of which the case is composed is so delicately
transparent that it is with some difficulty made apparent to the
eye; indeed, only by its fine filmy outline. In old specimens, however, it acquires a brownish tinge, and much extraneous matter
adheres to it. It is flexible, but not at all elastic; and apparently tough, without being viscid. Though, doubtless, a protection to the animal, yet, as with higher creatures, this
advantage is not without its dangers. I once saw a Stephano~
C01'OS whose case had been accidentally bent down quite to a
right angle, with many folds at the bend. The animal had no
power to straighten it, but protruded, with its foot correspondingly bent. I havo seen another, which, by some misadventure,
lJad got one of its arms entangled in the substance of the margin of the case. It coulcl not by all its efforts free the arm j
and, after much apparent annoyance, during which this member
evidently became diseased, the animal spontaneously forsook
the case. Thus it remained, the foot (wrinkled up, indeed)
projecting at a tangent, and the arm still fastened to the edge
of the case by its ciliary setoo. Under these nnnatural circumstances it soon died. While I am on these accidents, I may
mention the example of another individual which voluntarily
withdrew from its case. It was an operation of considerable
. labour and time j when the animal was clear of its tenement it
slowly moved along by alternate elongations and contractions,
but had no power of swimming. The foot presently wrinkled
up into a distorted form, and the animal survived only a few
hours. Doubtless, these forsakings are the expressions of the
creature's uneasiness and an indication of disease. Such acci.
dents should always be eagerly watched by the naturalist, as
he frequently obtaills an insight into structures and functions
when these are modified by accident or disorder, such as no
amount of patient investigation would have afforded him in the
normal condition of his subject.
The summit of the case commonly reaches as far as -tho neck,
or to the base of the arms of the animal when fully extendecl j
and it is attached by its base, around the foot, to the support,
as the leaves of 1J[Y1'iophyll~t?JL in my specimens. ':rhus the
animal is completely enclosed to the l1Gightjnst named, and the
only exit for the contents both of the ovary and the digestivo
e.
THE CROWN ANlMALCULE.
33
canal is at the top. In ejection the cloaca is much protruded
and turned upwards; the fmces are discharged into the space
between the body and the case-wall) and then gradually find
their way upward and over the rim. '1'he eggs are discharged
into the same cavity) and there remain till they are hatched;
the impressible substance of the gelatinous. case yielding to
make them temporary room; and the young when born struO'gle
gradually upward and outward to liberty. But this I ;hall
describe more in detail presently.
THE NUTRITIVE SYSTEM.-The internal organization of the
Stephanocm'os is complex, but the transparency of the tissuer"
at least when not occupied by the viscera, allows it to be well
discerned, notwithstanding' that the rays of light have to pass
to the eye through various organs, the integuments, and the
thick enveloping case.
The ciliatecl arms are carried commonly, as I have said, in an
inarching form (plate iii. a), inclosing a considerable vaulted or
somewhat ovate space. The setm, or vibrating bristles, are
arranged in whorls about fifteen or sixteen in number, but their
closeness at the extreme point precludes the attainment of
accuracy in counting. The whorls appear ill perspective liko
pointeclpencils) except on the arm which immediately fronts
the eye) where they take the appearance of the beards of a
feather. Those on the inside of the arms are seemingly much
shorter than those on the outside, and form little brushes
pointing upward.* Both arms and setm are commonly held
motionless j yet there is a manifest vortex in the inclosecl
area j for small IlIfnsol'ia approaching are presently drawn in,
and are driven about in the space. '11hey can enter readily at
all parts between the arms j but cannot get out, for if one
approaches the arms from within it is seen instantly to be shot
back towards the centre. At first I presumed this change of
direction to be a spontaneous motion of the imprisoned animalcules, for they were active wayward Monads j but I perceived,
after a while) a little inanimate atom have the same action;
and, after some careful watching, I found that it was caused by
the 'Setm; a minute, tremulous, and, as it were, spasmodic
wave being seen to run along the nearest pencils at the instant.
A slight jar of the stage or of the table will proclnce a similar
wave along ahthe poncils simultaneously, as well as a momentary opening of the arm-crown. It is clear) then, that the
setm, crossing each other, serve as a living net, which,ac1mits
the prey to enter without resistance, but if touched from within,
'*' Leydig thinks that the setre are planted in a granular stmtnl1l. external
to the cuticle, from which they are detached in bundles wllt'n subJected to
slight pressure.
NO. I.
n
34
POPULAR SCIENCE REVIEW.
vibrates in such a way as to jerk the touching: body with considerable force towards the centre of the contamed area. .
The preseuce of animalcules, especi~lly if active and hl~h~y
coloured, such as those of the genus MWl'oglenn?l' Eu~lena,* m
some abundance in the surrounding water, gIVes !'lse to an
iustructive and entertaining spectacle.
One by one they
quickly accumulate in the. living tra;p, .and. a dozen or twent~
may often be seen swimmmg about III ~t, tIll one after another
becomes engulphed in the deep cut-hke mouth-funnel below
the armS. When once they arrive here they rarely escape; but
the whole contents ofthe arm-trap are often lost at once by the
sudden retraction of the animal into its case, when all th~ p~'ey
0.1'0 left behind free to escape. Hence it appears that the VICtIms
are retained within the arms by the vortical current, produc~d,
probably, by the cilia which lir:-e the mouth:funnol, whose actIOn
is persistent durin?, the exte~~lOn o~ the .ammal; but that a~.~he
instant of retractIOn the CIliary VIbratIOn ceases, the vortICal
current is intermitted and when the arms are drawn back the
Monads remain wher~ they were, there being in that instant
nothing to prevent their passing between the tips of th~ arms..
But when once the prey passes down below the area m qu~s­
tion into the mouth-funnel, which is formed by very con,tractIle
walls, a slight constriction takes place in the neck, which has
the effect of forcing t~e Monad do~~ to the :nout.h of a capacious crop or p?'Ovent1'Leul~ts (plate 111. b), whICh he~ all aC1?SS
tho upper part of the body. ~ere a sort of s~allowmg n:~tlOn
is seen, and the prey paSses WIth a gulp down mto t~e caVIty.
This crop is formed of thick granular w:alls, whICh run up
in hio'h processes on the dorsal and ventral SIdes to the bases of
the ~'rms. Within the ventral one of these processes, at its
upper extremity, is inclosed a minute clcar oval body, perhaps
gla,ndular. ~;hero is an irregular row of similar but smaller
bodies running round the collar. An opaque, ill-defined, cloudy
mass is seen on each side, evidently resident within the walls
of the crop, in no wise produced or affected by its con~ents.t .
At the lower part and towards the dorsal side of thIS crop IS
placed the masticatory apparatus (plate iii. e), which consists
of thc ordinary jaws, evidently imbedded in the wall of the
crop, working freely in its cavity without an enclosing 1nastax·t
'*' These forms are considered by many observers to be "protophyfes," or
lowly organized plants.
t Dr. Leydig says the crop is furnished with four long bristles having
hoo]wd extremities, which appeal', by their resistance to lilJ.U01' potassw, to lle
chitinoils. These I have nob detected.
:\: I lmve elsewhere given the name of mastax to the conspicuous muscular
bulb, which in most ROTIl!'ERA contains the ji1WS, and which answers bo the
true mouth in insecbs, &c. (See my memoir "On the Mal1ducatory Apparatus
in the Rotifera," in Phil. Trans. for 1856.) .
35
Ehrenberg's figures ofthe apparatus in this species seem more
than usually incorrect; it is but fair to add, however that he
ac;lmits his' obseryation to be susceptible of doubt; a~d I can
glv.e my.own testImony to the exceeding c1ifficulty of obtaining
satHl~actIOn as ~o the real structure ofthese·minute organs. Accorchng to my Judgment, formed on many careful examinations
and ~hat in many specimens, each of the two 1nrJ,llei or upper jaw~
conSIsts of three curved diverging fingers, whose extremities are
united by an indented membrane like the foot of a water-fowl.*
'1'le inC1tS, or lower pair of jaws, consists of two very move.
able and widely-separated rami, shaped somewhat like a quarter of a globe, but much flattened, and each furnished with a
lengthened process, which unites with its fellow to form the
hinge, without a f~tlcrul1h The UnMtB is connected with the
1·(tr;1/tt8 by an elastic ligament, by which means the latter is
stretched open vigorously, while the teeth of the malleus act on
the prey imprisoned in the crop.
Let us now follow the engulphed, but yet ~igorous and active
prey. The crop we will suppose to be neadyfull of Monads, as
.1 have seen it to the number of a hundred or more; then we
perceive how ample is its capacity, for it descends, with the contained prey, far below the level of the jaws, while the individual
Monads on which the action of the jaws has been passing, often
return among their fellows. During life, and secn in [Lction,
the inC1t8, or lower pair of jaws, takes the form of a long oval
hox, partially open across the middle, or that of a pair of slippers
without quarters, placed heel to heel, so as to cross each other
at that part.
The two mall(li resemble hands continually
engaged in tearing apart the two sides of the box, or the toes
of the slippers, by which action the apertul'e is alternately
opened and closed, or rather made to recede and approach.
'1'he living contents of the crop come successively, but by no
means regularly, within reach of the jaws, and are dragged into
THE CROWN ANJMALCULE.
*
These constitute the uncus, the lower part of which forms a knob, inclosed in a muscular mass, which seems to answer to the ordinary ?IWlmbrimn.
For n full explanation of these terms, and the organs to which they are applied, I must refer to the memoir cited in the preceding note. I lUay say
here that It general idca of the a.ppil,1'atus of the mouth, which is very complex
in this class, ma.y be formed by supposing a. pair of gardener's shears, the two
hltndles of which are soldered into one, and thcn bent down at a right angle to
the blades. Then imagine two claw-hammers to be placed, one on each side,
working in the blades of the shears, to which each hammer is tied by an
elastic cord. 1nclose the whole in a great ronnded vessel, and fasten the
pa.rts to the interior by muscular bands, leaving an orifice with a tube over
the blades, and another benea.th and behind them, and you have a rough model
of a Rotifem's mouth. The shears are the lower jaws (incus), of which the
blades are the rami, and the unitocl handles the fulcrum. The hammers are
the upper ja.ws (mallei), the claw-head of which is called the unc1tS, and the
hanclle
the
The
vessel
represents the mastax:
..
. manubrium.
.. . .
. inclosing
.
.
D 2
36
POPULAR SCIENCE REVIEW·
the aperture between the slippers.. Her~ the mallei press ,up~n
the prey (suppose it ap Euglena), W1t~ ra:prd and forceful for';aI,d
movements, until they gradually drIve. rt through the aperture
downward. It is now free from the Jaws, b~t does not pass
into the stomach, but comes up around the srdes .of. the apparatus again into the upper area of the .crop,' and whrrlmg ar?lllld
with its companions, is presently agaI:dard. hold.of by the .J~ws.
I have seen the process go on many trm~s III qmck successIO~,
upon the same individual E1~glona, whrch see:ne~ to ~ustam
little damage from the ordeal; still, I suppose rt rs brmsed at
every turn, and thus the digestive action is faci.litated, which
seems to commence in the crop. That the prey rs not crushed
or its form seriously altered, is clearly p~rceived ~rom the fmces
which I have seen composed of the varIOUS speCIes of Monads,
&c., dead, indeed, and. mixed. with turbid green. matter,. but
scarcely at all changed rn outhne. Larger prey rs sometrmes
devoured, which cannot be forced through the apertu~e o! the
incus' thus I have seen in the crop at once two Oolun (mmuto
but hig.hly-~rganised RO'fIFERA), each of which. is larger than the
whole dental apparatus. The contents of theIr shells appeared
to be nearly dissolved.
...
Digestion is completed in a g~obose stoJ?la:ch (plate lll. d),
opening out of the crop below the Jaws. Thrs.rs a vrscus of c?nsiderable capacity, of which the walls ar.e thIckened by be~ng
lined with large t~rgid cells, of. a ,Yellowrsh-green hu~, whl?h
probably secrete brle, and pour It mt.o the stomacl;-cavrty w:hrlo
digestion is proceeding, thus perfor.mmg the fun~tI?nS of a Z~ve~"
The colouring matter of the foodrtself, when vrV;d g.reen alllmalcules have been swallowed, may be seen runnmg 111 among
the cells, and diffusing itself through the thickened walls, leaving a hue which is visible after the food has passe~ away f~'om
the tubular centre. The latter, the true stomach, IS very dIlatable and contractile. It is separated-by a constriction, or
perhaps by a proper dittphragm, sometimes very distinctly visible, but not always-from a globose intestine of nearly equ~l
capacity, which communicates by a rather long 1'(Jch~m, o~'dr­
narily wrinkled longitudinally, but capable of great expanSIOn,
with the cloaca, which, as I have said, is very protrusile.* It
"* Dr. Arlidge (Pritcharcl's ".Infusoria,". Ed. 4, p. 419) appears to confot:nd
the intestine with the ?'ect?1Jm III the entll'e class. I fincl, howevul.', no dtfllcnlty in clistinguishing, in almost all Boti/m'a, a tr:lO inte~tine, sitlUtte below
the trne dicresting stomach, from tt ?'eclnm, a call!tlmto wInch the fcccal11ellet
is discharg;d, and in which it occasionally rem!tins a fow minutes boforo it is
expelled through tho cloaca. By this last term I mean tho common orifico of
the digestive and the reproductive organs. Dr, Leydig considers, and I lllwe
come to the samo conclusion, from the same premises, lllyself~ that the complete and rapid manner in which the cloacal orifice closes, after tho oxtrusiqll
.
of thc foocal pellet, indicates the existence of a sphincteJ.' tnuscle t4ero;
37
is situated on the dorsal aspect, at the point where the swelling
trunk abruptly narrows to the origin of the foot (plate iii. 0).
Thus we have followed the alimentary function from its
commencement to its termination, and have found that an
organization, not a little elaborate and complex, is provided for
this object.
T~e Stephanocer'o8 is a voracious feeder. Ehrenberg saw large
NavW1~lce devoured by it, and in one individual a Gonium peetonde. . R~ also saw that .la:rge infusory, Stentor, captured by it.
Leydig wrtne~sed the se1zrng of a great 'l'raclwli1l1n, or various
other Infu8~na, and of the smaller Rotij'em. I have myself
seen the all1mal capture and devour scores of the Infusoria
already named, in quick succession; aIld on one occasion observed ~ne feeding ~n the :young of FloscuZaria digitata, which
were berng hatched III consrderable numbers in the same water.
THE
CROWN ANlMALCULE.
'l'HE REP~ODUCTIVE OR~ANS.-Tb e reproductive organs occupy
a ver:y consrderable portIOn of the bulk of the aIlimal, aIld are
suffiCIently conspicuous at all times in the adult. Judging from
analogy, I presume the Stephanoceros to be dioocious; that is,
that the males and females are distinct individuals; but I have
not had any opportunity of detecting the male, nor, so far as I
am aware, has any other observer. It will probably prove to
be very unlike the female, and to have much the same form as
the rudimentary young, before the development of the arms; to
be destitute of masticatory and digestive organs, and to have
a conspicuous mass of opaque white matter within the interior.
These characters mark the male sex in the ROTIFERAgenerally.*
.A. bent or rolled ovary (plate iii.f) occupies the greater part of
the ventral region ofthe female, withinwhich eggs maygenerally
be seen in various stages of development. I have seen as many
as seven eggs developing at one time in one individual. The
undeveloped portion consists of a clear sac, containing a viscid
granular jelly, often slightly turbid, in which are placed trans·;f Dr. Leydig mentions having found among Stephanoceri that he was
keeping for observation, a yonng animal possessing somewhat of the vermiform figure, with a proboscis-like head, furnished with four projecting arms.
Thc pair of eyes were discernible. Two considerable tubular appendages
projectecl from the tnmk-like l)rocess of the hcad, which were cilhtted at
their extremities; the cilia which at birth are set l.'ounel the tip of the foot
had disappeared, but were very evident in the abdomen, near the sac containing the atoms, which he considcrs urinary, The ,jaws had the ordinary
sl1'ncln?'e, He mentions having also occasionally found another variety, which,
tocrcther with the figure of the adult, hacl five arms, but was without any
aplJarent sexual organs, while the foot and body were entirely occupied with
fa~ globules. If either of these abnormal forms was the male, I conjecture it
was the latter; for the presence of the well-formedjttws in the former seems
to excludc that form from the masculine sex. Still it was. a very curious
variation.
38
i'OPtJLAil.
SClENdE REV'IEW.
parent) highly refl'acti~e globules) separ~ted by a spac.e abOl~t
equal to their own diameter. These are the eggs III theIr
primary rudimentary stage. The nucleus may g~nerally be
discerned in each as a dull spot, surrounded by a bl'lght space.
One ofthese eggs enlarges rapidly) and gradually becomes more
and more granular) until it is almost wholly opaque. It is now
become well defined, and assumes the size and yolk form
proper to the mature egg; but this shape is not constant, for
being as yet destitute of a shell, the soft and yielding yolk is
forced into ever-changing forms by the varying pressure of the
digestive and other viscera in their proper motions, and in those
communicated to them by the inflexions and contractions and
elongations of the body.
.
Meanwhile, what is termed segmentation of the yolk takes
place. The turbid, semi-opaque mass may be seen to be divided
across the middle into two masses, each of these into two
more j and so on, until the whole has become a mulberry-like
mass of small cells. When this stage is reached, the dull
opacity di~appears, and is replaced by translucency, in which,
however, we begin to discern a complex array of organs
and viscera. The egg now contains a living embryo, whose
movements within its enveloping integument as well as those
of some of its organs, as for example, its jaws and its vibratile
cilia, can be discerned with ever increasing distinctness. These
motions are rendered more distinct,-are more readily determined to be proper to the embryo, and not communicated from
theviscera ofthe parent,-by the circumstance that the envelope
has now hardened to a firm, elastic,perfectly transparent shell,
accurately elliptical in outline, from the internal wall of which wo
see the embryo recede at various points, waywardly and irregularly. Besides the organs I have named, two crimson specks
may be seen near one extremity, and an opaq llO, undefIned mass
at th~ otheI> Both of these are seen to more advantage 1)y using
the dIrect hght of the suu reflected from the stage of the microscope with a dark background. Then the red specks come out
perfectly defined, and of the richest vermilion hue, in the midst
of the ev~nesce~t viscera, and the opaque posterior spot is seen
to be qmte whlte. The former are the eyes, which I shall
speak of presently j the nature of the latter is not ccrtrtln.
Dr. Leydig supp~ses it to be an urinary concretion. It is very
frequently seen III newly-hatched young ROTU'ERA und in the
males, I think, always (see plate iv. fig. a).
DEVELOPMENT OF TRill EMDRyo.-Dr. Mantell was the first to
observe the development of the young in Stephanoee1'lJs' and
in his (( Thoughts on .Animalcules he has recorded'some
interesting results of his investigations. I have myself verified
J)
'rIlE
CROWN
ANIM.ALCULE.
39
his observations for the most part, and have also extended
them. I shall speak of what I have seen, except where my
experience differs from his.
Between the most matured egg in the ovary and the cloacal
orifice, lies the oviduct, a membranous tube of great expansibility, but when not in use longitudinally corrugated so as to
occupy a very slender space. When quite ready, the egg is
rapidly forced through the oviduct, and in a moment escapes
through the protruded cloaca into the interstice between the
body of the parent and the wall of the enveloping case, the
gelatinous substance of which yields to the pressure of the intruding egg. Here it lies close to the cloacal orifice for a short
time, varying from half an hour to several hours, at the end of
which the young' is hatched (plate iii. g). In one instance
which I watched from the discharge of the egg to the hatching,
the escape from the shell took up several minutes, and appeared
a laborious task, reminding me of a caterpillar becoming a
chrysalis. In general the liberated young slowly presses its
way upward between the parent and its case, till it emerges at
the margin; but the one that I have just mentioned made its
way through the side of the case near the top, boring, as it
were, a passage through the gelatinous substance by means of
. its vibrating cilia j the force of the ciliary currents apparently
abrading the soft jelly atom by ntom. Dr. Mantell mentions
one which penetrated through the bottom of the case, a process
which occupied three hours befo1'e it obtained freedom.
.As soon as the young is free from the parental case, it swims
vigorously away. Its length is now about one-hundredth of an
inch, or nearly one-sbcth that of the adult (plate iii. h). Its
form bears a rude resemblance to that of the parent, except
that there is no trace of the coronal arms. The front is rounded,
well set with strong vibwitile cilia j the body is cylindrical, with
many transverse corrugations, and a short thick footis distinc~ly
marked. The interior is occupied by a granular, often turbId,
gelatinous flesh (sa;rcode), in which are placed many: irregular
bubbles (perhaps 011 bubbles), a few large bladder-hke organs
(the rudiments of the fnture v~scera), traces of the five. muscular
bands, which subsequently WIlll11ove. tho arms, the Jaw~, :vell
formed and situate near the middle of the body, two brIlhant
red eyes near the front, and the opaque white urinary mass
near the site of the cloa,IJ[~.
Having swum giddily about for a whi!e,-longer or s~orter,
from a few minutes to half an hour,-;-It becomes statIOnary,
finding a resting-place for its foot. In the live-box of the
microscope it generally affixes itself to one of .the glass s.urfaces.
The specimen which I have before .montIOned, WhICh was
hatched under my eye, s,vam for ten mlllutes, and then became
POPULAR SCIENCE REVIEW.
permanently attached to the upper glass of the box) so that it
was vertical in its position) with the foot next to the eye-a
favourable aspect for observing the development of the case.
It presently began to dilate its body) and in ftbout five minutes
from its attachment) I perceived a distinct filmy ring around it)
perfectly circular, whose diameter was about twice that of its
body (plate iv. fig. b). The little animal now began to lean over
to one side) and the ring soon had another segment additional)
leaning in the same direction (fig. 0). The case) for such it
was) looked like two broad hoops of glass) each swollen in the
middle aud set one on the other, but not quite concentrically)
at least to the eye of the observer. It was manifest that it was
produced by an excretion from the body) owing its form and
size to the animal's moving round on the foot as on a pivot.
Three hours after the hatching, the form of the young animal
was elongated and maggot-like (in another instance the young
was eight hours in attaining this stage) while others in the same
period had the arms well formed and furnished) (fig. f); the
case having the appearance just described. No trace of the
arms had as yet appearec1. Night intervened, and the next
morning, eleven hours after birth, the arms were beautifully
formed) and of considerable length (fig. g); the mouth-funnel
was well marked) and the general shape had become charaeter~
istic: the case had increased in dimensions. At eighteen and
twenty-four hours) I found the arms becoming more and more
perfect) and at thirty-six hom's after birth it was a perfect little
6'tephanoceros (fig. i), the outline of the body well developed)
the princi.pal viscera, the collars)the mouth-funnel, the muscular
crop, the Jaws-all distinct; the ciliary setre were now arranged
in whorls of pencils) and vibrated on a slight jar; the « urinary"
concretion behind remained, apparently within the intestine, as
a sort of meconium. Indistinct traces of the opacities of the
crop began to be discernible. In the animal at this age, the
arlllS) which have attained the full proportional length) are
carried1l1uch more divergent than usual) and it occasionally
expands the coronal circle nearly to the extent figurecl by
Bhl'enberg in the adult.*
"* I have not inftny case seen the first buddin~ of the 111'111S fro111 the rounded
front. Bnt Mnntell mentions (and refers to hIS figures, which are, however,
very indistinct) It cluster of foUl' or five sub-conical papillm, which in a young
thirty-hours' olel were perceptible "1vithin the botly," and which he supposes
to Imve been "the l'lldimentltry rotatory organs," in other phrase, thc arms.
Then, again, he mentions, eighty hours after birth, the young as beuJ:'ing
"~ve ll1am1Uilla~ecl. projectio"ns, fringed with cilia on the upper margin,
eVIdently the 1'lldiments of the tentacula." These latter were doubtless what
]l(l supposes them to have been, but in the former instance I have some
suspicion that l1e merely saw the points of the brachial muscular bands (see
the fi::r. of young in plato iii.). He figures a yet furthor development at
THE
CROWN ANIMALCULE.
41
CIRCULATION AND RESPIRATION.-The performance of these
functions in the ItOTIFERA is involved in a good deal of
obscurity, as is shown by the diversity of opinions that have
been expressed on them by the most careful and judicious
observers. I have but little light on the subject derived from
the Stephanoceros) and must, therefore) consider it with reference to the entire class.*
In almost all ROTIFERA there is seen towards the hinder extremity of the body) usually in contact with the cloaca, a
bladder, which is often of conspicuous size, sometimes occupying' half the volume of the abdominal cavity) or even more)
as in some of the Brachioni. It is known as the contractile
bladder. Under the eye of the attentive observer it is seen
gradually and insensibly to be distended, until it attains its
full dimensions) when) from its extreme clearness) its welldefined form (which is generally globular, or nearly so» and
from the fact that it pushes aside the su.rrounc1ing viscera)
it is very conspicuous. No trace of corpuscles, moveable or
stationary, can be discerned by the most careful scrutiny in
its contents; yet no one can look on it without feeling quite
assured that it is distended by a fluid. Over the walls, in
some species) may be discerned numerous filaments irregularly
ramifying and meandering.
When the bladder has attained its utmost degree of distension
it suddenly contracts on all sides, and wrinkles up to a barely
perceptible point. The action does not occupy so much as a
second; and as soon as it is accomplished the process of repletion goes on as gradually as before, and is followed by contraction in turn. The act of filling is called the diastole, the
emptying the systole. The periods of contr~ction are generally
uniform in the same iudividual) but sometImes they are very
irregular.t The average interval may be perhaps set down
at about fifteen seconds.
eil1hty-four hours in which, however, they are not quite so advllncee~ as
mine in the earlie~t state in which I noticed them, at seven hours after bIrth
(plate iv. f). The comparison of these da~a s~ows ho~ e?,~remely varying ~l1d
nncertain are the periods of development 111 different 1l1~IVldual~.. They.differ
greatly cvcn when the conditiOl:s appcar exactly alIke; as 111 specImens
hatched in the same live-box, 111 the same water, from the same brood,
and on the same day.
'*' I must beg my reltdel"s indulgen.ce if my desc;iptions appear s.ome~vhat
obscure. I have laboured to be as SImple l18 possIble; .but the subject ltself
is intricate and difficult and cannot be understood w1thout some personal
acquaintance with the ~bjects. theJl!selves,. as viewed ~ith the microscope.
The future pllpers of this senes, WIth thOlr figures, WIll help to make the
subject much more intelligible.
. ,
.
t They recur most rapidly, so far as my eXp!ll:lence goes, lU the. Monoce?cadre; thus in Monoeerca ?'attus the contractIOns are about. thirlee~ per
minute, and in Mastigoecl'ca carina/a I have counted twenty-five III the mmute.
42
POPULAR SCIENCE REVIEW.
In Stephanocerosthere is a rather sma:l but cle~r blad.d.el'
(pI. iii.) placed behind the rectum, the fillIng of which I have
repeatedly seen, but have never been able to catch clearly the
contraction. Not that there is any doubt about the process, but
I believe the animal invariably retracts its entire body at the
moment of the systole, so that the process cannot be perceived
in the confusion.
In connection with this curious organ there are others equally
remarkable. Two bands are seen passing along longitudinally
through the entire length of the trunk, one on each si~le, in
most of the ROTIFERA.* They, for the most part, conSISt of
threads, apparently tubular, hanging somewhat loosely, so as to
form bends, which are invested with a thick corrugated envelope.
Sometimes the tube forsakes the enveloping matter and passes
straight along, while the coating forms a great bight. In some
cases only one of theso tubes can be seen on each side, but in
others two, or even four, can be distinctly traced, loosely twisted
together. 'l'he corrugatod coating seems to consist largely of
fatty matter, and may be intended for the protection of the delicate tubes. It is particularly copious in Stephanoceros (pI. iii.).
These organs, which are called by pretty uniform agreement
reslJ1rratory t~~bes, have never been satisfactorily traced to their
anterior termination. t
Posteriorly, the extremities of tho two tubes converge to the
*
They are excellently well seen in Asplanchna, in Notommata claV7ilata,
in N. au?'ita, in Euchlanis, and in B?'achionus.
t Professor Huxley, describing them in Lacin1ila1'ia, says, on this point,
"Arrivecl at the level of the pharyngellJ bulb [mastax] each vessel divides into
three bmnehes : one passes over the pharynx [buccal f7mnel] and in front of
the phar,YlIgeal bulb, ancl1mites with its fellow on the opposite side, while the
other two pass, one inwards ~nd the other out;vards, in the Sptle~ betweeu
the two layers of the trochal dISC, llud then tC?'m~nate as creea. BeSIdes these,
there sometimes seemed to be another branch just below the paueren,tic
saes." Possibly S0111e of these al)parent branchings 111ay have been only
threads of couneeti ve tissue, whose purpose is to fasten the tubes to the walls
of the abdomhml Clwity. I lllwe never been able to trace allY coalescence of
the anterior extremities of these organs iu any slJeaies. In Brachion'u8 I lllll
quite satisfied that each vessel terminates (whether by nn open or Cl0881l end I
do not know) ill the .linillg-membrane of the loriea close to the lateral frontn,l
spine; for the vigorous rctraetations of the moveable head-mass do not at all
affect the relative positions of these vessels, nor throw them into curves. Iu
Euchlc~nis, on the other hand, they termh1!\te iu the head-mass itself, mul arc
not attached to the lorica. In Stephanoce1'os I luwe sometimes thonght thab
there was such It eonnexion of the vessels as Mr. Huxley speoJes of; for tho
cuyious. little tre,nmlous bags (whieh I shall presently describe) aro found
eluefly III the regwn of the neek, armnged around the second collar, but I
have not beeu able to detect their attachment, I lllwe seen five ab once DU
this level, which seems inexplieable on the supposition of the supporting
vessels passing only longitudhullly on each side. I saw another tag DU tho
dorsttl side, a little below this level, and (in another individual) two ltt oue
levelllearthe bottolU of the stomach. (PI. iii.)
'rItE dROWN ANIMALCULE.
43
surfaco of the contractile bladder, and seem to me to ramify over
it entering it by many mouths. One ofthose accidents which we
c~n never command or control, butwhichareoftenhighlyinstructive, gave me a little insight into the nature of the tormination
of these vessels. Examining a specimen of Monocer'ca, porcellus
which I had killed by means of the compressoriurn, the sudden
and strong pressure severed the tortuous respiratory tubes and
forced them out of the shell (lwica) hanging from the he.ad-mass.
They now appeared like crumpled cords, cove~'ed. WIth close
transverse lines,· probably the effect of corrugatlOn III contracting j and from their posterior ~e~ions mr;-ny short ~ate1'al
bramches were given off, the eJ:trern~tLes of whwh hnd emclently
beenjorcibly tom from theitr ctttachm(Yflfs. I have never seen any
tendency to a trumpet-like expansion of the posterior extremities of the tubes, at their entrance into the bladder, as
LeydiO' implies nor caU I call this latter organ f( a dilatedstl:itte
ofthebunited e~ds of the two respiratory canaIs/' even m$tephanoc(J?,os. Small as it is in this species it appears to.beofthe
normal structure.
The most remarkable part of the whole apparatus, however,
is the series of minute tromulous bodies which are attached. to
the respiratory tubes, much li~e th~ tags of roll~d p~\per wInch
are tied on to the pendent taIl-strlllg of a boy s lnte. . In all
the larger ROTIFERA the watehful. eye ca~ches,. from tI~o to
time, a tiny object that has a waverlllg' motlOn, hke tho .flIckering of a flame. Oft~n it eannot be detect.ed at all; often oll.e
only, or two such obJect~ are caught; but I~ fav~urablo condItions we may generally dIscern foul' on each SIde (111 Asplanchna
B?'1:ghtwellU more than a dozen) attached to. each tUbe.,.,
Ehrenberg was more happy ID; tho fl~nctI~n he ascnbed t~
these minute organs, than III hIS phY~lOlog1~al nomenclature
gonerally. He says, (( 'rhoir function IS ~'espll'atory, an~ they
are analogous to gills: the tremulous motIOn observable IS that
of the lumd!J1.C8 composing them." Here, however, he was
misled by the deficiency of. his instr~l~e~lt, and spo~o too
confidently from mere ~onJectur~. Ih61r structur~ ,IS not
laminated. They are eV1dently httlo ovate, or pem-shaped
vessels seated bv a short foot-stalk on the respll'atory tube
and pI:ojecting i;;'to the body cavity so freely, that they a:'e
swayed hither and. thither by every moyeme.nt of th~ flll1~l
with which tho body is filled. Tho..fhckermS' motIOn. IS
seen to be produced by a single ?Ilium, whICh. OCCUplOS
the interior of the liUlo tag, runnmg throl1&,h. ItS centre
lel1gthwiso, attached near its free end, and yomtmg ~own­
ward to its· base. A rapid waving mo~emont. IS comml1ll1cate~
to the. cilium, which is at ploasuro mtermItted; . and. so It
is quite common to sea only one or two tagsfllCke1'll1gat
4·1
POPULAR SCIENCE REVIEW.
THE CROWN ANIbrALOULE.
once. Somtirnes the tags appear triangular or broadly pearshaped, sometimes nearly cylindrical, or slightly elliptical.*
Such are the forms of the organs, so far as they can be
determined. It remains to investigate the function and the
mod~18 ope1'Clndi.
The first question is, what becomes of the contents of the
contractile bladder at the systole? It is exceedingly difficult
to trace the outflow of the fluid, and I have watched often
and anxiously with the utmost care to detect this, in vain. Is
it discllarged into the cloaca, and so effused from the body? or
is it poured into the respiratory tubes, and so passed into the
system? Analogy would lead one to conclude the former to
be the case j but, as I say, it. is very difficult to see it. On
one occasion:, however) I saw this decisively. Oarefully watching a specimen of Notomrnata clamilcltcl, having previously
mingled carmine with the water) I observed that the region
of the rectum situate between the bladder and the cloacal
orifice was distinctly puffed out at the instant of the contraction) and now and then I discerned, quite indubitably, that
the minuter atoms of floating carmine were shot away by a
discharged jet d',eau. Thus the excretory office of the b'ladder
was decisively proved.
"Whence, then, comes the fluid that is so discharged? Some
have supposed that it is derived by direct and immediate percolation from without, through the cloaca.t Others believe
that the sac is filled from the tortuous vessels. Dr. Leydig
adopts this hypothesis. He believes that the water enters the
general cavity from without, either by endosmose,t or by
minute orifices hitherto undetectcd, aud then mingles with the
products of digestion, absorbed through the thin walls of
the intestine, to form the (( chylaqueous fluid JJ of Dr. Williams)
-the analogue of blood in the superior races. The effete
water is then directed through the tags by their open ends) the
vibrations of the inclosed cilium imparting the inward current
to it, and sointo the bladder. I quite believe this to be the
true state of things; and therefore, that the respiratory tubes
represent the kidneys, and that the, bladder is a true urinary
bladder. Thus in INSEOTS, with which class I consider the
ROTIFERA most closely allied, the kidneys exist in the form
of long, often tortuous tubes, generally from four to eight in
number, and often those of each side twisted loosely together,
in which uric acid has actually been detected; while in some,
as the water-beetles (Dyticidce), there is a voluminous urinary
bladder.
If this explanation be according to fact, it follows that the
respiratory and urinary functions are in the closest relation
with each other.
~ ~hese llave been described as of two kinds. I find, however, that the
varlat'l?n depends on the aspect in which they are viewed. In a specimen of
Bmchton1tS elQj'cas I casLUtlly obtained a very satisfactory view of one of the
ta~s in the line ?f its long axis, when it was manifestly a flattened body. The
trIangnlar for~n IS, then, that of the flat-the sub-cylindrical that of the edn'e.
Cohn, correctmg the error of Leydig, Ims also given this explanation.
'"
t. Mt. Dalrymple su~gests that the bladder draws in water, ancl expels it
agalll! .by the cluacal onfice, and that it is by bringing the blood, by Ineltns of
the Clhary movements of tllC tags, into immediate contact (the delicate mcmbranou~ w~lI o~ the sac intervening) with the air of the water, that acmtion
or ~'eslmatlOn IS IJe.rformed. M. Perty adopts this explanation. Dr. Colm
heheves that he proved the existence of this incommCl' current as well as at'
the outg?ing one, in Brcwhio'l1Jlts milita?'is, a Sllccics l~culiarly' flwoumble for
o~ser~atlOn, Ol~ account of .the enormous developmcnt of the bladder. On
ml1Jghng co!ourll1g matter WIth the water, Cohn says he witnessed an inward
current dm'lug each dilatation, and an outward one on each aot of oontraction
alternately.
'
:j: !J1ndosl1~ose is that law ~y 'Yhich a tI~in. fluid pa:~ses through !!' mell~1Jrano
to !l1l1lg1e WIth a denser flmd 111c10secl ll1 It. (It IS fully descl'lhecl 11l the
paper on " The Lowest Forms of Life."-ED.)
45
THE NERVOUS SYSTEM.-The nervous matter in this class
exists in a remarkably concentrated and conspicuous form)
constituting a cerebral mass) which, for its proportionato
volume may compare with the brain of the highest VERTEBRATA. ) Ono is amazed to find such an organ in the lowest
type of the ARTIOULATA, so compact, so well-defined, s~ large;
and it is not without considerable hesitancy that we are mduced
to admit its right to a cerebral character. Yet the~'e eau be no
reasonable doubt, that such it is. Its position in the anterior
region of the animal, and usually with.a dorsa~ aspect; its
rounded outline, and· compact figure; ~ts greJlsh, granular
texture; and, in particular, the connection .with it of t?e eye,
which is invariably seated like a wart upon It,-revea~ Its true
character, which, so far as I know, has not been questIOned by
any observer.
.
. .
Leydig does not recogl1lze the bram 111 Steph((,1WCe~'~8 j* y~t
I find it clear and indubitable, though small. (PI. lll.) It IS
placed on the dorsal side, just beneath the second collar, behind
the upper part of the crop, and immediately beneath the
* I do not l11ean that he has not described and figured th~ organ, but !le
does not recognize its function or homology. l;Jnder tl~e tItle at' "SpoClfll
Organ," he has ~hes~ words: " Iml11ediat~ly over the crop ,~s fOlmd a stl'Uctur~,
the value of whlCh 1~ unknown to lIle. It IS a group of veslCles, clear as watel,
which tOCl'ether forl11 a hody '024 line in diameter, which ~pens by a s!l?rt b~lt
evident passage in the cu~icle," Thi,s i~ certainly the bram. Its PO~ltl~n, Its
conformity of structure WIth the bram l!l other ROTIF;'Jl!l:A, and the seatmg of
the red eye-point on its rotundity, which I ~ave chStlllctly seen, leav~ no
doubt on the point. The orifice he alludes to IS paralleled by 'Yhat I beheve
to be nntennal orifICes in.Asplcmclmct, and hy an actual,antenna III Notom:nata
olCW1tlata, to whie~ mtlsp~llar and UerVOUS threads go chroct t'rom the [mun,
46
47
POPULAR SCIENCE REVIEW.
THE CROWN ANIMALCULE.
integument, which, in some specimens, makes a very distinct
bulging or tumour to receive it. Iudeed, the form of the organ,
which is vertically pear-shaped or ovate, is always to be
traced in the exterior outline. Its substance is delicately
granular. I have not been able to trace any nerve-fibres given
off from it j but around the fron tal expansion, just at the base
of the arms, goes a bttnC! of substance (pI. iii.), evidently very
different from the muscular bands, and apparently not vascular,
which is connected by branches with another broader band,
that passes round at the upper collar j descending branches
and threads go from this also,and appear to pass to the walls
of the mouth-funnel and crop. These are probably nerves. I
suspect there is a nerve-thread, which passes centrally through
the entire length of eaeh arm.*
On the upper part of the brain, and on its anterior (or
ventral) surface, looking forward across the crop, is seated a
minute but well-defined eye. By transmitted light it can
scarcely be detected at all, and hence, probably, it has been
usual to consider the organ as obliterated ill infancy j but, under
the rays of the sun, thrown on the object by means of a COlldenser, and reflected from it, the eye comes out sharp, distinct,
and beautifully red, as if a globule of rich opaque vermilion had
been placed among the clear pellucid flesh. I have no difficulty
in finding it in adult specimens, by this mode of examination.
In the newly-hatched young there are two eye-spots. Row
these become changed into the single eye of the adult I do not
know j I suspect by coalescence. I have, on more than one
occasion, seen th1'ee eye-spots in a mature egg, of which one
WttS miuute, and under the others.
I should have thought it
an accidental monstrosity, but that I remarked it in two eggs.
They were not prismatic spots, nor oil-bubbles, but globular
'
specks, of opaque red, seen undor sunlight. t
transverse band immediately after the commencement of tho
divarication) the individual muscle-bands join the annular band
at remote points. Such seems the usual order, but it is not
invariable j for in some specimens I have seen muscle.bands
which seem to run down direct ft'om the intervals of the arms)
without uniting to form pairs. The longitudinal muscles pass
through the foot) having) as I suspect, an insertion into the
walls of the body near the origin of this member, by whose
aiel the ~oot can be thrown into strongly-marked transverse
corrugatIOns.
Besieles the annular band mentioned, there is another which
passes round the neck, unconnected with the longitudinal series,
at the level of the first collar j and there. are threads which are
contractile, and therefore, I presume, mnscular, which pass from
side to side of the walls and processes of the mouth-funnel. I
have not been able to trace any of the special musoles of the
trunk, though doubtless such exist.
.T~E M USC.UL~R SysTEM.-In its more prominent features,
thIS IS very dIstmct. A muscular band runs round the frolltnl
disk, at the base of the arms, forming a low arch, or bow, in
the swell of each arm· base. To this annular band are attached
strong longitudimtl bi1nds, which run through the wholo IOllg'bh
of the body.. T~ese are associat~d ill pairs, miming side by
slde-fi~e ~all's. ll1 all,-each ,Pall' ~xactly corresponding to
an arm m directIOn. Each pt},}r begll1s to sepal'ate at the levol
of the upper collar j and, having been connected by a short
'X'
Seo infra.
1- Thero is 110 doubt at all that t,he crimson specks found on the bl'l1in in
1110S~ ROTIFERA are real eyes. The
cerlllble.
.'
lens, in SOIne s!)ecies, is distinctlv dis.;
.
DrsEASEs.-I have already alluded to the tendency of the
8tephmwce1'os to disease. One ourious malady it seelllS rather
subject to. The foot attenuates, and soon appears to be tlissolving in some parts. Wb.en the dissolution has extonded
through its thickness, the animal draws up the proximal portion
that remains, and thus, having now no cOllnoxion with the
gelatinous case,' becomes free. 'l'he arms now become feeble,
and can no longer maintain their beautiful mitre-like form, but
expand widely j parts of the visoera also appeal' dissolving, and
sometimes there is a protrusion of the intestines. Yet strong
contractions of the body and vigorous working of the jaws
still go on, twelve, eighteen) or even more hours after these
symptoms have manifested themselves. At length the arms
deoay at the base,. and become separa,te, when one part of each
swells out intp a large bladder, doubtless by the expansion of
the gases formed ill decomposition) and reveals an item of
structure which is not discernible in health. 'l'hrough the centre
of the swollen part runs longitudinally a cord, which, from its
granular appearance, and its resemblance to the bands that
pass round the head, I judge to be nervouS matter. The arl,ns
seem peculiarly liable to disorder. Often, towards the extremIty
of one, minute bubbles appear in the substance j these increase
in number, and take the appearanoe of a congeries of minute
black specks j soon that part of the arm sloughs off, and thus
it is common to see a Stephanoceros with one or mOre arms
reduced to stumps.
The arms are capable of being constricted, bent nearly at an
angle, or drawn up, with close-set wrinkles, into a very short
space. This last process sometimes occurs with one arm alone;
48
POPULAR SOIENCE RE VIEW.
sometimes with all at once. One in my possession, from a
perfect condition, so shortened all the arms (not, however, while
under my eye), that they were reduced to the merest rudiments
or tubercles, retaining a few of the pencils of setre j and though
these subsequently lengthened a very little, they did not become
normal again.
Of an individual which I had found in health, the foot,
the next day, separated itself from its attachment by t~e
sloughing of a portion, leaving a ragged edge. T~e body dId
not withdraw from the case. The foot went on to dIssolve away
upwards, in a very ragged f~rm: about the third day the arms
became shrunken, flat, and distorted. The setre were now seen
to be of great length j they vibrated still when jarred, and now
and then spontaneously. Under these circumstances the nature
of the vibration was far more discernible than in health. I
could now distinctly see that each seta bent laterally, and then
straightened itself like a whip smacked j the flexion was performed sudde:z:tly, the extension gradually. The flexion appearecl
to be fi.'om south to west.*
The animal is not difficult to keep alive in jars of fresh water,
exposed to the light, but guarded, of course, from the hottest
rays of the sun. The water-plants on which it lives attached
are essential; but these need not be rooted. Fragments of
MY7'iophyll1~m, OeratophylluJn, Nitella Pota?nogeton) &c.) may be
detached, and will continue to live and grow while submerged.
I have kept Stephanoceros for five or six weeks.
I do not know any other localities in the British Isles for the
species than those which I have mentioned. But it is widely
spread on the continent. Eichhorn found it at Dantzig, exactly
a century ago) and figured it in 1775. Ehrenberg rediscovered
it near Berlin in 1831) and afterwards saw it on several occasions.
Weisse met with it once at St. Petersburg. Perty)s Stephanoc61'os glaciaUs) found by him in Switzerland (in the Todtensoe,
on the Grimselhiihe), was probably only a deformed and diseased
specimen of S. Eichho?'nii.
Such is the history) so far as I have unravelled it, of the
largest, the rarest, and the most elegant species of the class
ROTIFERA. ·A.n exquisite form it is) and one whose structure
THE CROWN ANIMALCULE.
and habits will) I have no doubt, abundantly repay investigation
by careful observers with good instruments, as there are many
points in its economy on whioh we need further light.
EXPLANATION OF THE ILLUSTRATIONS.
PMTE Ill. ropresents an aclult female Stephanoccros Eichhornii, magnified
one hundred diameters. A young one, just hatched, is seen within the
parentaJ case, working its way upward to liberty.
PLATE IV.-Metamorphosis and development of the s~me. Fig. a, The ogg
just ready for hatching: b, The young, fifteen minutes after birth, permanently
nttached with the first elements of the case deposited: c, The same, twentyfive min:ltes old, with a new segment to the case: cl, Another indiv!dual, four
hours old: c, Onc, threo hours old. The developlhent in these two IS at about
thc Sltme point, hut that of the case in c, though thc younger, is rather tho
more advanced: j, (f, h, Intermediate conditions, from six to twelve hours
old: i, The adnlb form perfectly developed, at thirty-six hoUl's after birth.
Figs. V, c, c, (f, ltnd i, represent the same individual. In each fibrtlrc, the foot
of the nnimalmust be understood to be adherent to the jal'lhcr surface of a
plate of glass, and the ease to he attached around it, so that both animal amI
ease projecb jl'oln thc eye.
For fuller information on all that has been published eonce1'lling this species,
the reader is referred to Ehrenberg's Memoil', in the" Berlin 'l'mllsuctions"
fOl' 1831, and his" Infusiollsthierchon ; II to Dr. Mltntell's "Thoughbs on AI~i.
lllltlcules," and to Dr. Frnnz Leydig's admirable Mcmoir on the 1l0Tm.E~A, Ul.
Siebolcl and Kolliker's "Zeitschrift," for July, 1854. The new cdlblOn of
Pritchard's " Infusorilt" (1861) contains a vltluablo summary of the researches
of the continental savans on the whole class, including, of course, the present
species.
*
I use this mede ef indicating eircular metion, IJcel\Use it is IJreciso : wc
have only te suppose the plane ef the eh'cle to bo horizontal, and no mistake
can pessibly be made. The ordinary Ilhrase, "fl'omloft to riglrb," er 1Jice versa,
is .indefinite and ambigueus, because "right" and "left" are opposite pointfJ of n
circle, and motion from onc te lhe elher nJU,y bo in opposito directions. If to
des~ri?e the sun's uPI1urent I?lOtion as "~rom ~eft to right" is in~elligiblo with
us, It IS only because a port.lon of lhe CIrcle IS 11c)1oath tho horIzon. ,At the
t101es it wellld be cluite ambiguous.
.
NO.
r.
10