ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
173 
He Geer, Freyana anatina Koch. He begins with notes on the ova — 
their form, envelopes, &c. ; he describes a very distinct germinal vesicle 
in Psoroptes ovis , though this body is usually not to be detected in the 
ova of Acarina. The blastoderm plate shows five pairs of rudimentary 
appendages ; the first give rise by proliferation to mandibles and palps, 
the other four become limbs. The author lays emphasis on the clear- 
ness with which he has been able to show four pairs of limbs in the 
embryo. When the larva issues from the egg it has only three pairs 
of limbs, but in the succeeding nymph-stage there are again four. On 
account of the developmental peculiarities of Acarina, the author would 
rank them as a distinct sub-class of Tracheata. 
e. Crustacea. 
Physiology of Decapoda.* — M. C. Saint-Hilaire thinks that his work 
has been inadequately appreciated by Cuenot. For before Cuenot he 
pointed out that food was absorbed in the midgut gland. He adheres 
to his conclusion that the vacuolated cells do not produce the ferment. 
According to Cuenot, the vacuolated cells, besides producing ferment, 
eliminate injected pigment directly from the blood. Except methyl-blue 
the pigments simply diffuse out, but are not “ excreted.” According to 
Saint-Hilaire, the injected pigments penetrate first into the cavities of 
the tubes and are then absorbed by the vacuolated cells ; it is impossible 
to fix a limit between excretion and osmotic penetration as Cuenot does. 
Saint -Hilaire’s general view is that the midgut gland regulates the 
composition of the blood and of the formed juices. 
Lobster Reproduction.^ — Prof. S. Garman draws attention to a report 
of his, published by the Massachusetts State Fishery Commission, in 
which he appears to have anticipated many of the results recently related 
by Mr. F. H. Herrick.J He found that the female Lobster lays eggs but 
once in two years. As the normal time of laying is when the water has 
reached its summer temperature, that time varies in different seasons 
and places. The eggs do not hatch before the summer following that 
in which they were laid, and the time of hatching also varies as the 
temperature. 
Action of Gravity on Nucleolus of Lobster.§ — Mr. F. H. Herrick 
has a note on an unexplained phenomenon in the egg of the American 
lobster. He finds that the nucleoli of all eggs are eccentric and all lie 
on the same side of the nucleus. Experiments showed that the supposi- 
tion that this was due to gravity acting directly upon the nucleolus was 
correct. The ovary of a lobster was cut into several parts, and these 
were hardened in different positions. It invariably followed that the 
nucleolus fell, from its own weight, to the lower side of the nucleus like 
a shot within a tennis ball. It is pointed out that this phenomenon is 
a direct result of the structure of the nucleus and the action of gravity. 
There is no trace whatever of a nuclear network. 
Development of the Body of the Prawn and the Crayfish.!] — M. L. 
Roule has for some years been engaged in the study of the development 
* Zool. Anzeig., xvii. (1894) pp. 349-52. t Tom. cit., xviii. (1895) pp. 38-40. 
x See this Journal, 1894, p. 677. § Anat. Anzeig., x. (1895) pp. 337-40. 
II Comptes Rendus, cxx. (1895) pp. 27-3. 
