ZOOLOGY AND BOTANY, MICBOSCOPY, ETC. 
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similar to that given by Nusbaum for H. lutescens. At an early stage 
Korff finds three centrosomes in the spermatides, but one of these dis- 
appears, leaving a proximal and a distal. He describes the elongation 
of the proximal centrosome, and its conversion into the axial filament of 
the middle piece of the sperm, but was not able to follow the changes of 
the distal centrosome beyond the early stages. His paper and that of 
Nusbaum seem to have been published almost simultaneously. 
Factors in Morphogenesis.* * * § — Dr. 0. L. Zur Strassen discusses the 
possible formative factors in development, and concludes that too much 
importance is attached by 0. Hertwig and others to the environmental 
influences. The really determinative factor is in the fine internal me- 
chanism. “ It is as if the segmentation-cell had a guiding instinct.” 
This is illustrated by cases where the blastomeres move spontaneously 
but definitely. Tensions and pressures are insufficient to explain the 
changes of form and the cytotropic wanderings. 
Development of the Common Phalanger.f — Dr. R. Broom has made 
some observations on the breeding habits and the development of Tri- 
chosurus vulpecula. Only one young is produced at a time, and the 
breeding season varies a little, but usually begins in March. The young 
begin to breed when about a year old. No trace of an allautoic placenta 
could be found. The paper includes descriptions and figures of several 
young stages both intra-uterine and mammary. 
Development of Siphonops annulatus.t — Dr. Emil A. Goldi com- 
municates a brief note on a discovery of the eggs of this Amphibian in 
the Orgel Mountains, Rio de Janeiro. The mother and eggs were found 
in a very dry situation. The former was coiled round the string of eggs, 
which were six in number. They were perfectly transparent, and in 
size 10 mm. by 8J mm. They contained well-developed embryos, in 
appearance very similar to those of Epicrium glutinosum. The fact that 
breeding takes place in dry situations is of interest in view of the fact 
that the gills of the embryo are very well developed. 
Development of Snake’s Poison-gland.§— Dr. H. Martin has studied 
this in an embryo of Vipera aspis. It begins as a single bud, which 
divides on the one side into a bud growing towards the fang-apparatus, 
and on the other side into a venom-rudiment. The latter gives rise to 
three structures, namely, in order of their appearance, — a Y-shaped 
organ (game gingivale ), a poison-canal, and the poison-gland. The 
embryonic development of the parts occurs in an order the opposite 
of that of the venom-flow in the adult. 
Lateral Sense-organs of Fishes. |] — Mr. E. J. Cole has studied this 
subject with special reference to the genus Gadus. He finds that the 
sensory canal system of all fishes can be reduced to a common type. 
This type includes a lateral canal on the body, one canal over the eye 
and another beneath it, and one related to the lower jaw. All these 
* Verb. Zool. Ges. Heidelberg, 1898, pp. 142-56 (10 figs.). See Zool. Centralbl., 
vi. (1899) pp. 400-2. 
t Proc. Linn. Soc. N.S.W., xxiii. (1898) pp. 705-29 (4 pis.). 
X Zool. Jahrb. (Abtb. Syst.), xii. (1899) pp. 170-3 (1 pi.). 
§ Bull. Soc. Zool. France, xxiv. (1899) pp. 106-16 (13 figs.). 
|| Trans. Linu. Soc., vii. (1898) pp. 115-221 (3 pis.). 
