ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
607 
distinctness in embryos of Sycandra raohanns. In the history of the 
ovum, there is first a growth-period in which an amoeboid cell becomes 
a definite ovum ; then a ripening period, in which the germinal vesicle 
becomes smaller and more compact, and gives off polar bodies after 
mitotic division ; then follows fertilisation, which leads immediately to 
the first segmentation division. The longitudinal axis of the first 
spindle always lies exactly in the longitudinal axis of the ovum. The 
illustrations showing spindle-figures with polar radiations and distinct 
chromosomes (of which the normal number seems to be 32) indicate a 
quite typical mitosis. 
Protozoa. 
Deep-water Rhizopods.* — Dr. Eugene Penard has made an exhaus- 
tive study of the Rhizopods of the depths of the Lake of G-eneva. He 
gives lists with notes, descriptions, and figures of the characteristic 
forms, and contrasts the fauna of the Lake of Geneva with that of some 
other Swiss lakes. The Rhizopods flourish best at depths of from 30-50 
metres; below this they seem to diminish both in number and variety. 
Although the physical conditions of light, pressure, and temperature are 
virtually constant throughout the year, the fauna is not constant, being 
smaller in winter than in summer. This is no doubt due to the fact 
that the Rhizopods depend for food on the diatoms of the upper waters, 
and these decrease or disappear in the winter months. As to the general 
characters of the deep water forms, it is noticed that they tend to reach 
a large size ; in this respect they are contrasted with the more highly 
organised inhabitants of the same depths. Among other peculiarities 
are the apparent partial loss of functional power by the contractile 
vacuole, and of the power of encystation in many forms. Though sym- 
biosis in the strict sense is impossible, some forms (e.g. Difflugia elegans 
var. teres ) seem to possess the power of keeping the diatoms of the food 
alive and assimilating within their protoplasm for some time. 
As to the origin of the Rhizopod fauna, the general similarity of the 
deep-water fauna of the Swiss lakes seems to be against the hypothesis 
of its independent origin in the different lakes. The only suggestion 
which the author has to offer is that this fauna is the remnant of a 
widely distributed glacial fauna. 
Experiments on Difflugia.f — Dr. Eugene Penard found that separated 
pseudopodia of D. lebes and D. pyriformis behave for a short time like 
small amoeboid organisms, but die in a few hours. Placed near the 
“parent” individual, a pseudopodium is attracted towards it and rejoins 
it; but its behaviour is just the opposite if the individual near which 
it is placed is not its “ parent.” 
Notes on Foraminifera.J — Prof. A. Silvestri describes the Pliocene 
Biloculina globosa Soldani, and shows that it merits distinctive specific 
rank ; while the variety eristata of Peneroplis pertusus is allowed to be, 
as F. W. Millett and L. Rhumbler declared, merely based on specimens 
which have suffered corrosion. 
* Rev. Suisse Zool., vii. (1899) pp. 1 142 (9 pis.). 
t C.R. Soc. Phvs. Nat. Geneve ; in Arch. Sci. Phys. et Nat., viii. (1899) p. 90. 
% Atti Aecad. Pontif. Nuovi Lincei, lii. (1899) pp. 68-73 (3 figs.). 
2 s 2 
