ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
299 
Development of the Nervous System and Vibratile Organ in Larvae 
of Compound Ascidians.* — M. A. Pizon has studied a number of com- 
pound Ascidians, especially Fragarium and Amaroucium. He finds in 
these that the vibratile organ is a portion of the primitive endoderm 
vesicle, as it is in the buds of all compound Ascidians. This organ is 
formed independently of the vesicle and nerve-tube. Its connection 
with the vesicle is accidental and temporary, and Hjort’s error in 
believing that the vibratile organ was a remnant of the nerve-tube was 
due to his not having studied sufficiently young stages. As to the 
definite ganglion of a fixed oozoite it is a product of the larval nervous 
system, as the author has already observed in the Botryllidse and as 
Hjort has seen in Fistajplia. 
Mollusca. 
a. Cephalopoda. 
Habits and Reproduction of Rossia macrosoma.-j* — M. E. G. 
Racovitza gives an interesting description of the habits of this cuttle- 
fish. It buries itself, like Sepiola , in the sandy bottom ; feeds on small 
crustaceans and fishes ; and seems to have a short life — probably a year. 
In spring, the males and females are small, with slightly developed 
gonads ; in August and September they are mature. The copula- 
tory region in the female and the hectocotylus-gland of the male 
develope greatly. Copulation probably occurs as in Sejpiola ; the sper- 
matophores, directed by the penis into the funnel, reach the mantle- 
cavity of the female probably along a special groove. Along this groove 
they pass to the receptive region, where they are glued by the secretion 
of the hectocotylus-gland. There they burst, introducing the end of the 
spermatophore-tube under the skin, and form a second series of sperm- 
reservoirs. 
The two arms of the male inserted in the mantle-cavity of the 
female during copulation, hinder her from breathing ; hence her 
resistance and the straying of spermatophores. 
After copulation and the disruption of the spermatophores the mem- 
brane of the sperm-sac bursts, the spermatozoa are scattered, and 
fertilise the ova just as these pass from the oviduct. The almost 
spherical eggs are laid singly, each within a resistant yellowish shell. 
They are often grouped on shells and the like. The hectocotylus-gland 
is an invagination of the epidermis of the grooves which separate the 
rows of suckers. The supporting cells are got rid of at sexual maturity 
and the epithelium becomes wholly glandular. 
So-called “White Body” of Cephalopods. } — Herr V. Faussek 
discusses this strange tissue or organ which lies between the eyeball and 
the optic ganglion of Cephalopods, within the common ectodermic 
sheath. Its structure in the adult suggests that it is an area for the 
formation of blood-cells ; the development shows that it arises from the 
ectoderm in close connection with the nervous system. It is difficult to 
bring these two facts together. Schaffer indeed speaks of the ectodermic 
* Comptes Rendus, cxx. (1895) pp. 462-4. 
f Arch. Zool. Exper., ii. (1894) pp. 491-539 (3 pis., 6 figs.). 
X Mem. Acad. Imp. St. Pe'tersbourg, xli. (1893, received 1895) pp. 1-28 (1 pi.). 
