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359
They test the hypothesis with species of known spawning habits,
comparing southern North Sea herring with pilchard, and North Shields
haddock with hake. The spawning periods of both pilchard and hake are
known to be long, while those of the herring and haddock are more
restricted. It was duly found that in the two former there was no sharp
separation between the ripening quota and the main egg-stock, while, in
the two latter, clearly defined groups were present.
The suggestion that such measurements of intra-ovarian eggs may be
used to provide information regarding species the spawning habits of which
are unknown should now be in general acceptance. The writers cite several
investigators who have used similar methods, although they have omitted
perhaps one of the more extensive of recent works upon the subject,
"Maturity of the California Sardine (Sardina caerulea) determined by Ova
Diameter Measurements", by F. N. C l a r k (Div. Fish and Game, Calif.,
Fish. Bull. No. 42, Sacramento, 1934).
The paper concludes with an important rider to the effect that the use
of H j o r t's scale of maturity stages encounters difficulties when applied
to a fish of prolonged spawning period, for as the eggs contained in the
ovary are progressively ripened and shed, the ovary itself grows smaller
and to the naked eye appears to reverse the stages by which it attained
its full maturity. .
D. S. R.
E. Lea and A . E. Went. "Plastic Copies of Microscopical Reliefs,
especially of Fish Scales." Hvalradets Skr. Nr. 13, pp. 18, 6 Plates.
Oslo, 1936.
The authors restate the considerations favouring the senior author's
suggestion that multiple replicas of fish scales be provided for exchange
among investigators in several countries. (Lea, E i n a r. "The Herring's
Scale as a Certificate of Origin." Rapp. et Proc.-Verb. LIV, 1929).
The technical procedure for preparation of such replicas is as follows:
Cleaned scales which have neither been allowed to dry nor subjected to
the action of coagulating preservatives (storage in alcohol is permissible if
dehydration is accomplished by a gra'ded series of alcohols) are glued,
sclerotic side uppermost, to very carefully cleaned glass plates with glycerine
jelly. The spiny portions of ctenoid scales are coated with glycerine jelly
individually. When thoroughly dry the exposed surfaces of the scales are
rubbed with a solution of castor oil in acetone to prevent sticking in
subsequent processes. The surfaces of the glass plates bearing the scales
are carefully brought in contact with sheets of celluloid the surfaces of
which have been thoroughly softened with a mixture of acetone and amyl
acetate. Care must be taken to avoid entrapping air bubbles. After the
softened celluloid has set under moderate pressure for a time, it is carefully
stripped off and the sheets are attached at their margins to wooden blocks.
When thoroughly dry, an indefinite number of exact positive replicas may
be cast from the moulds formed in the celluloid plates, by flooding the
latter with warmed glycerine jelly which is hardened with formalin, allowed
to dry, and then stripped off the plate.
The very fine illustrations demonstrate the marked superiority of the
replicas to the scales themselves.
The reviewer has experimented sufficiently along similar lines to be
convinced that no substantial simplification of the rather elaborate process
is possible if the original scales are to be preserved unaltered, and if exact
360
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and uniform positive replicas are required. Negative moulds can be prepared
more quickly and more conveniently by methods requiring sufficient pressure
to force the scales into unsoftened or slightly softened celluloid, or into
soft metals, but only at the cost of slight stretching of the original scales.
Also, if the additional step of casting positives be omitted and a series ot
negative impressions of a single scale be prepared for exchange by pressure
methods, uniformity must be sacrificed, for there is a progressive stretching
of the original scale when repeated impressions are made. (With cod scale>
the total diameter of the twentieth impression exceeds that of the first
by about 1-5 per cent.) Consequently, the method described is to be
recommended in preference to pressure methods in those cases in which
preservation of the original scales or maintenance of exact uniformity in
the product is of greater importance than the saving of time and labour.
R. A. Nesbit.
H . B . M o o r e . "The Biology of Littorina littorea. Part I. Growth of the
Shell and Tissues, Spawning, Length of Life and Mortality." Journ.
Mar. Biol. Assoc, N.S., Vol. XXI, No. 2, pp. 721—742, 10 Fig.,
1 Plate. Plymouth, 1937.
The material used by Dr. M o o r e in his investigations into the biology
of Littorina littorea was collected from three localities near Plymouth in
which the conditions differed considerably. The specimens were collected
by hand-picking, and, in the case of the representative samples, by sieving
a surface sample of ground from an area of known size. The samples were
collected at approximately monthly intervals. The methods employed in
examining the material thus collected are described in detail in the paper. The
rate of shell growth in the first and second years is described for each area,
and the results are shown in a series of graphs. The size-distribution figures
being useful only up to an age of about two years, after which the successive
peaks overlap too much to be distinguished, for finding the growth-rate of the
larger sizes marked individuals were employed. In a number of periwinkles,
the sex of which had been determined, it was found that growth proceeded
faster in the females than in the males. No ripe females were found on the
grounds before early February, but spawning proceeded rapidly from then
until mid-March, although some females were not yet completely spent at
the end of May. The age at first maturity, and at the first considerable
spawning, is given for each of the three localities examined. The mortality
rate is discussed in some detail. The paper, which contains a number of
explanatory diagrams, is a valuable contribution to our knowledge of the
biology of Littorina littorea.
p 5 ^7
G. I. Crawford. "A Review of the Amphipod Genus Corophium, with
Notes on the British Species." Journ. Mar. Biol. Assoc., N.S., Vol. XXI,
No. 2, pp. 589—630, 4 Fig. Plymouth, 1937.
Die vorliegende Arbeit enthalt ein Verzeichnis aller bis jetzt bekannten
Arten der Amphipoden-Gattung Corophium Latreille, 1806, im ganzen 32,
sowie ausfuhrliche morphologische und oekologische Angaben iiber die in
Grossbritannien und Irland beobachteten Arten, im ganzen 11, darunter
3 neue.
Die Corophien leben in seichtem Wasser und bilden alle, soweit bekannt,
Rohren aus Schlick oder schlickigem Sand, entweder im Boden selbst oder
auf Schwammen, Ascidien, und ahnlichem Substrat. Manche sind besonders
haufig in Flussmiindungen und Hafen, wo ihnen viel Schlick zur Verfiigung