396 SUMMARY OF CURRENT RESEARCHES RELATING TO 
Glandular Character of Umbilical Vesicle.* — Dr. Graf Spee shows 
that the epithelial covering of the human umbilical vesicle developes 
into a distinct glandular tissue. This is clearest about the end of the 
third week of pregnancy. He regards the tissue as a simple hepatic 
tissue, discharging at an early date functions which the liver after- 
wards performs. 
Mullerian Duct of Crocodile.t — Dr. Gregg Wilson describes the de- 
velopment of the ostium abdominale tubae in the crocodile. His results, 
taken along with Wiedersheim’s, indicate that the Mullerian duct is 
derived from tbe thickened coelomic epithelium that appears first round 
the pronephric nephrostomes, and afterwards extends backwards to give 
rise to the perfect tube. 
Oviposition of the Snapping Turtle.:}: — Prof. K. Mitsukuri has made 
a study of the number of times the Trionyx lays eggs in one season. 
He comes to the conclusion that during certain warm months of the 
year, May to August, when the temperature is within certain limits, 
successful crops of eggs rapidly mature, and are deposited as soon as 
they mature. As a general rule, three or four deposits are thus made 
in the course of one season. The difference in the number is mainly due 
to meteorological conditions, but perhaps also to some extent to other 
circumstances, such as the healthy condition of the ponds, the age of 
individuals, and the supply of food. 
Blastopore of Frogs’ Eggs.§ — Mr. J. B. Russell wishes to direct 
special attention to the fact that in the development of the frog the 
alimentary cavity is formed as a narrow slit-like aperture. This slit 
rapidly grows inwards and spreads out beneath the surface of the egg, 
near the future dorsal surface of the embryo. The history of develop- 
ment shows that the hypoblast, which lines the embryonic canal, is 
derived from yolk-cells. 
j8. Histology. 
Mechanism of Cell-Division. || — Prof. W. Flemming allows that 
Driiner’s interpretation of the central spindle as a supporting organ, 
which keeps the poles apart, has much to recommend it, but he adheres 
to his position that the polar rays have a directive and attractive action. 
He admits, also, that he was inaccurate in speaking of a centrifugal 
shortening of the polar rays as the condition of the divergence of the 
poles ; all that he meant was a change of tension. 
Altmann’s Granula.l" — Dr. G. Zanier supports, against the[criticism 
of A. Fischer and others, the view that Altmann’s granules pertain to the 
normal structure of protoplasm, and are expressions of its inherent vital 
activity. He lays emphasis on the uniformity of their occurrence in 
embryos as well as in adults, in fasting as well as in normal animals. 
Structure of Nucleus.** — Dr. G. Catterina gives a brief history of 
research as to the structure of the nucleus, and adds his own observa- 
* Anat. Anzeig., xii. (1896) pp. 76-9. f Tom. cit., pp. 79-85 (8 figs.) 
t Zool. Mag., vii. (1895) pp. 143-7. 
§ Trans. Hertfordshire Nat. Hist. Soc., viii. (1895) pp. 129-30 (1 pi.). 
|| Aich. f. Mikr. Anat., xlvi. (1895) pp. 696-702 (4 figs.). 
If Bull. Soc. Veueto-Trent. Sci. Nat., vi. (1896) pp. 63-7. 
** Tom. cit., pp. 67-76. 
