ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 399 



pronuclei occur sometimes at the germinative pole near the directive 

 amphiaster, but usually at the other end of the ovum. They move very 

 slowly in the vitellus, which at the most advanced stage observed did 

 not possess a vitelline membrane. M. Garnault notes in conclusion that 

 M. B. Blanchard has also suggested that the male pronucleus developed 

 at the expense of the substance of the germinal vesicle, but has given no 

 evidence, and further that the observations above summarized in regard 

 to the male pronucleus hardly agree with what Platner has described in 

 Avion. 



Mantle of Gastropods and Dependent Organs.*— M. F. Bernard 

 continues his investigation of the structures associated with the mantle 

 of Gastropods. 



(1) Monotocardii ; false bipectinate gill. The author has previously 

 described tho structure of this organ, but adds some notes on the nervous 

 terminations. In the epithelium, outside the basilar membrane, tho 

 terminal ramifications of the nerves end in a network of multipolar cells. 

 The terminal cells end in little rods, often reduced to minute heads 

 plunged in the pigment of the non-ciliated epithelial cells which sur- 

 round them. The neuro-epithelial cells may be distinguished by the 

 absence of cilia. 



False gills with a single ganglion have been observed by Lacaze- 

 Duthiers, and by the author in Vermetus, Paludina, Littorina, Bithynia, 

 &c. His observations on Cyclostoma agree with those of Garnault. 

 The peculiar structure of the false gill of Paludina is described. 



(2) Diotocardii. In reference to the observations of Spengel, 

 Bouvier, and Wegmann, the author maintains that there is in the 

 branchial support of Diotocardii no trace of rudimentary gills; the 

 branchial ganglion and nerve are exactly as in Littorina. 



(3) The structure of the false gill is not essentially different from 

 that of other portions of the mantle, but the neuro-epithelial terminations 

 are more numerous, more constant, and better grouped. Their sensitive 

 function does not seem doubtful ; but to say that they are olfactory is 

 premature. 



(4) In Prosobranchs, in all the organs associated with the mantle 

 and with the foot, there is neither cartilaginous nor capillary structure. 

 The modifications of connective, muscular, and epithelial tissue differ 

 only in the proportions of their elements. Thus neuro-epithelial, 

 secretory, pigmented, and indifferent epithelium occur throughout, but 

 in certain regions (tentacles, false gill) the former predominates, and the 

 regions become sensitive. In the mucus-glands, purple-glands, and 

 certain parts of the branchial lamellas glandular tissue predominates. 

 All parts seem equally adapted to respiratory function. 



Kidney of Monotocardate Prosobranch Gastropods.t— M. E. Perrier 

 has examined particularly the renal organ of Littorina littorea. He finds 

 that the secreting apparatus is composed of a series of anastomosing 

 lamellae, one edge of which is attached to the wall of the renal sac, 

 while the other hangs freely in the cavity. Along the short edge there 

 is a vessel, the walls of which are distinctly bounded, and it extends 

 throughout the whole of the lamella. The renal vessels all arise from a 

 common trunk which has its origin in the sinus which surrounds tho 

 intestine ; they contain venous blood, divide frequently, and convey the 



* Comptes Rendus, cvi. (1888) pp. 681-3. t Ibid., pp. 7G6-8. 



