We wish now to learn why this quite complicated structural transformation exists, what advantage it has for the aim of dividing the
individual nucleus into two halves. Inasmuch as here is an elemental ·
process which almost all cells must go through in their division, but
which requires time and energy, it must therefore have a ver)' evident
jmrpose in order to have been developed gradua.lly ancl retained. Thus it
must be in accord with biological needs in much higher degree than the
time, energy and structure saving process of direct halving of the nucleus
by tying it off through its middle.
·
·In case the purpose of nuclear division were only a simple halving of
. the "mass" of the rwcleus and the spatial separation of the two halves
from each other, it is evident that the process of indirect nuclear division
[mitosZ:s] represents an enormous detour to this close goal and that it thus
would be altogether purposeless.
·
The outcome would be otherwise if the objective of nuclear division
is not just any halving of the nuclear mass, but, some kind 0£ "definite"
separation also of the "qualities" which comprise this mass.
Let us imagine for example it is to halve a mixture of various substances in such a way that, in each half, also half of each ancl every
substance present finds qualitative hal1Jing. In order to attain this objective we will stir and shake the mixture of substances as well as possible,
until it is assumed all substances are completely equally mixed and
distribu tecl in the entire mass; if we now halve the mass by division
through the middle, then the objective is attained. This method is very
simple; it unfortunately does not always lead, however, to. the goal: for H
is suitable then only if under otherwise favorable drcumstances so much
substance of every qualityis present that it c~n be equally divided within
the whole remaining mass. Moreover, th.i.s method will be applicable
without disadvantage only in the case where suCh an equal mixture of all
the constituents does not lead to alteration and decomposition o[ the
qualities through mutlial interaction;
If, however, only so little of each substance is present that at the most
lt is divisible only into a rather small number of similar bits, or if any
mixture of the qualities will riot withstand alteration, then the problem
of halving the entire mass, as well as halving of the mass also of each
individual quality, becomes a very great one.
The "smaller" .the mass of the whole structure and the few'er the
number of qualities of the total to be halved, the easier it is. to solve the
task under these conditions, since in both cases it is that much easier to
establish a uniform mixing and since through this each quality comes
into ever less contact with other qualities.
·
We can attain both if we divide the mass to be thus qualitatively
halved into smaller and smaller pieces; through this in each piece remains
Wilhelm Roux (1883) On the significance of nuclear division figures. A hypothetical discussion.
From Gesammelte Abhandlungen iiber Entwickelungsmechanik der Organismen, 2: 125-143
(Leipzig: 1895).
what was together and what fitted together. The number of qualities in
each individual bit simultaneously becomes less with the mass of the bit.
If this mechanical sj)litting is carried on so far that there. are ji1st as many,
or even more, bits as qualities in the entire mass, and if we now precisely
halve the mass with respect to each piece ancl lay the one half of every
jJiece to one sicle, the other half of every piece to the other side, then the
smn of all the jJieces on the one side will rather j)erfectly equal that on
the other side, not only in mass, but also in qualitative comj;ositfon and
percent composition. The more the number of primary bits exceeds that
of the qualities, the more perfectly will this purpose be reached. If thereafter, in the mechanical division of the whole mass, consideration is made
that those parts, which lay next to each other in the undivided mass also
came to lie next to each other again in the pieces, then no damaging
.
·
interactions of them on each other take place. ·
Jn this kind of division, however, much must be carried out by
hand with the help of discriminating intelligence, without which these
can be accomplished only by means of. certain mechaiiical devices; this
particularly applies during and after the halving of the primary parts for
the proper division of these halves to e<icll of the two deposit places.
The a.ct of "dividing" the material into small bits, that is the
"primary division," must cak.e ·place by itself, without external help, ·
·whether it be by active coristriction or clecentration with perfect disposition around the new center, or in some other manner.
The pieces thus formed must however be situated from the outset in
a definite manner in order later after their halving to be able to be
directed with certainty, in each of their halves, to the correct jJlace. The
simplest form for this purpose 1vould be the disposition to a one~la.yered
plate, whi.ch provided its two stirfaces to the futuren1eetirig place of the
division produc;ts; If, then,_ all the granules which constitute the plate
are halved in the direction .of the plate it can thus suffice for the correct
separation of the halves, if only.the halves of a granule have the capacity
reciprocally to repeII each other. They will be properly separated tl1en by
this repulsion· and driven deeper into their future regi<m. This wotilcl
occur even more certainly if in. each 0£ these regions an attraction center
[e.g., the spindle pole] were found, which actively pulled the granules to
the center.
In case, however, these division processes do not take place in absolutcl y motionless surroundings, if on the contrary clefon'nations appear
clue to external agitations, disorganization will still easily arise, despite
these two ordering and reg·ular-clivicling strengths, disorganization whi.ch
could be the cause of the transfer of the two halves of the. same granule
to the same side. This could be prevel1ted, however, despite such disturbing influences, if arrangement were. t~_at each still undividedgranuJe qe
Wilhelm Roux (1883) On the significance of nuclear division ~gures. A h~potheti~al discussion.
From Gesammelte Abhandlungen uber Entwickelungsmechanzk der Organzsmen, 2 · 125-143
(LeiP_Zi~ 8~-
situated on two of the [spindle] threads which come from the .two future
centers [j>0les], so that itfter the division each divided granule is imme5liately situated on a thread upon which it can safely be conducted to its
_destination without disturbance, even if lively movements in the vicinity
push the pieces against each other, provided only that the transporting
threads themselves are not torn 01' separated from their center.
Thus, through such a triple mechanism, the security of the appropriate behavior of every halved granule can be very great and also be
protected against external disturbance. It is strengthened even somewhat
more, if each related pair of halved granules also always remain connected by a thread after theii· separation from.each other, since through
this, the conducting threads on both sides will unite in to a figure complete in itself, and thus have a greater stability. In this case external
disturbances, which possibly could lead to. entanglement and severing ·of
threads, could better be withstood.
This arrangement suffices for simj1le conditions. As long as only few
and relatively large granules form the equatorial plate, one can imagine
that the arrangement of the particles into a uniform, one-layered plate
through.sticking together or through attraction of the granules together,
can sufficiently safely be attained as long as they are polarized.
It will be more difficult if the number of mother granules to be
halvecl is very lm-ge, when the granules themselves are very small. Still
more difficult will be the situation in.which the mother granules; because
of too great number, are absolutely unable to come to a one-layered
arrangement in .the space available for the. equatorial plate.
Let us initially discuss the first case (for which the latter case is
indeed still possible), where. the large number and the tiny smaHness of
the mother granules make necessary; however, certain protective arrangements for the preservation or restoration of order in the equatorial plate,
especially when external distttrbances occtir. The formation and maintenance of the one-layered arrangementwould seem to be facilitated if it
is not left to chance how the organized granules maintain themselves in
this arrangement. Although they might, perhaps by a temporary force
effect, come to a plate through mutual attraction or through clumping,
the one-layered arrangement will be facilitated if continuously, tightly
regulated forces are employed. Since two kinds .of effects are to be produced, at least two kinds · of forces will be necessary: a force 1vhich
produces and maintains the stratification of the granular order, and if
necessary restores it, and a force which brings about and maintains connection to the plate.
In this discussion we do not have to concern ourselves with special
causation, but rather to consider these only to the extent that allows us
to judge whether our purpose can definitely be attained through such.
Wilhelm Roux (1883) On the significance of nuclear division figures. A hypothetical discussion.
Fro~n C:-esammelte Abhandlungen iiber Entwickelungsmechanik der Organismen 2: 125-143
_(~e1pz1g:} 895).
'
Let us consider that the granules are firmly arranged on stratified
"threads." This easily happens afterall, by itself, namely, as long as the
granules are polarized and in so far as at the same time passive external
motion is not absent. This subsequently gives the solitary, laterally
attached gnnules the opportunity to fit in, by means of a loosening of the
connection through bending in the rows. One easily observes this with
floating magnets on corkballs which are oppositely stuck with two magnetic, steel drawing pins. This mono-layered arrangement, then; is a very
solid one, for it will bow in the case of external influences, but afterward
it will again stretch, since the effect of the individual magnet totals up to
a large bar magnet which .is in inner equilibrium only in the stretched
condition. Moreover, this causal diversion will also. be gotten around here
if we restrict ourselves purely to formal considerations, and consider the
firmly formed thread-rows as given. If, however, in order to make sure of
the certainty of the arrangement, we inquire about such guaranteed
forces, a better source will scarcely be found.
If 110.w these threads are brought together by a strong central force, a
very solid. arrangement is made with these· two kinds of forces, one in
which the only thing lacking is the arranging of the threads within the
equatorial plate. This can be taken care of by means of the central concentration. Naturally the threads themselves may not be loriger than the
available space of the equatorial plate measures.
The one simple, easily maintained grouping, of the equatorial plateinduced stringing of the mother granules into threads can guarantee yet
a further real advantage, namely that in division of .the granules, it transfers itself to the daughter granules in such a way that through this
division, the mother thread, by maintenance of the arrangement, splits
itself along its length into daughterthreadS. In.this case with respect to
the outward movement, of the daughter pieces to the new center, now
only one "conducting filament" is needed for each individual daughter
thread composed of hundreds of thousands of granules; instead of one
conducting filament for each individual granule. The magnitude of this
advantage cannot be overestimated. For if each of the thousands of
g1·anules required a separate filament, quite aside from the tendency .of
so many filaments to become entangled, the great number of the.m
would be altogether unable to converge from the same side to a common
point. On the other lnmd, h would also be a great waste of conducting
material, if a .filament which had the strength to withstand relatively
powerful external tractions had to serve only for the attachment of a
quite insignificant load. This simplification can be increased still more,
without damage to the certainty 0£ the separation arising, if two neighboring mother threads always move together at the central end and unite
into a loop. The loosening of the daughter threads from each other and ·
Wilhelm Roux (1883) On the significance of nuclear division ~gures. A h~potheti~al discussion.
From Gesammelte Abhandlungen uber Entwickelungsmechamk der Orgamsmen, 2. 125-143
(Leipzig: 1895).
__ _
-----·-~~-
---- .. ------------------·--·
their conduction to the new center is not really made more difficult by
this and the conducting material is decreased by half. This. uniting· of
threads may be found howeve1: only on that side where the separating
force takes hold; if on the contrary it were on the opposite side, here also
at the periphery, then tangling and tearing of the thread loops arise
later in the loosening· and separation. of the daughter threack This would
be caused by a traction proceeding outwards from the central end,
Thus, we have become acquaititecl with the necessity and the
advantages of an arrange·rnent of the granules into threads ancl into
thread lopps . . .
·
·
Our purpose was the halving of an array of substances ... not only
the entire mass, bl1t also the mass of every individual quality ... within
a closed space and exclusively through the forces of the materials present
. in this sjJace. We thus have. recognized an intricate number of processes
and fonnations as indispensably necessary, or as leading the 1nost simply,
to our purpose, and which correspond in .all details with the" processes
and formations which have been observed as the typical ones of .nuclear
division andwhich were mei1ti6ned at the beginning of our discussion.
Wilhelm Roux (1883) On the significance of nuclear division figures. A hypothetical discussion.
From Gesammelte Abhandlungen iiber Entwickelungsmechanik der Organismen, 2: 125-143
(Leipzig: 1895).