ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
57 
artificially reared forms with similar food, but without succeeding in 
diminishing the mortality. Further, they find that in highly differen- 
tiated larvie like those of Cottus bubalis, a condition of marked anaemia 
can be shown to begin before the food-yolk is used up. They believe, 
therefore, that it is not wholly want of food which causes death, but 
some radical defect in method which acts injuriously upon both eggs 
and larvae. They are in consequence unable to assure themselves that 
the larvae liberated from the stations do survive even with the environ- 
mental change, and express themselves as sceptical not of the utility of 
marine pisciculture but of present methods. 
Breeding Habit of a Japanese Tree-Frog.^ — S. Ikeda has an in- 
teresting note on the breeding habit of Bacophorus Schlegelii Giintb. 
They pair in April and May immediately after awakening from hiberna- 
tion. The females are always larger than the males. With the male on 
her back the female makes a round hole in the muddy banks of paddy- 
fields, ponds, and lakes, and spawning may be finished by the next 
morning. There is some evidence that the spawning may also take 
place on trees. 
The eggs, when laid as stated above, are enveloped in a white jelly- 
mass full of air-bubbles, and of spheroidal form. This frothy envelope, 
like well-beaten white of hen's egg, protects the egg from external 
agencies, perhaps prevents overcrowding, but especially facilitates the 
respiration of the eggs and embryos. The outer surface dries into a 
crust, the air-bubbles within secure aeration. Ikeda gives a detailed 
description of the treading and kneading movements of the female which 
work the jelly into froth. 
Segmentation is unequal and total, but shows a closer approach to 
the meroblastic mode than other amphibian eggs. The early develop- 
ment has some striking resemblances with that of Ganoids : — (1) the 
embryo is greatly flattened over the large yolk-mass, so that the ventrally 
observable organs, such as the heart and the liyo-mandibular arches, 
appear in front and at the side of the head ; (2) the body of the embryo 
in later stages is wedged into the yolk-mass, which is deeply grooved 
along the dorso-median line. 
Interstitial Cells of Testis. t — Prof. K. von Bardeleben concludes 
that the interstitial cells ( Zwischenzellen ) of the Mammalian testis are 
originally epithelial elements which, like mesenchyme elements, leave 
their original association and become migratory. He regards them as 
contributing to the nutrition and liberation of the spermatozoa. 
Axial Filament of Human Spermatozoa J — Dr. Fr. Meves finds that 
in man, as in the rat and salamander, the axial filament of the sperma- 
tozoon has an extra-nuclear origin, from one of the two central cor- 
puscles, namely from the one which is nearest the periphery of the 
spermatid. 
Dimorphism of Spermatozoa in Mammais.§ — Prof. K. von Bardeleben 
thinks that the facts of spermatogenesis in Monotremes, Marsupials, 
* Annot. Zool. Japon., i. (1897) pp. 113-22 (2 figs ) 
t An at. Anzeig., xiii. (1897) pp. 529-36. 
t Op. ci\, xiv. (1897) pp. 168-70 (2 figs.). 
£ Op. cit , xiii. (1S97) pp. 564-9 (6 figs.). 
