ZOOLOGY AND BOTANY, MIOROSOOPY, ETC. 941 



has been led to results somewhat diflferent from those of Ihering and 

 Sabatier. 



According to Sabatier, the ova are formed at the expense of the con- 

 nective cells of the ovarian wall. As they grow they raise the connective 

 padding (feutrage) which surrounds them. They are covered by a non- 

 cellular membrane. Nuclei arise within the protoplasm and shift to the 

 periphery. 



M. Garnault maintains that the ova arise from a germinal epithelium, 

 that the follicle consists distinctly of cells homologous with those which 

 form ova. The iuternal corpuscles said to move to the periphery are not 

 really nuclear, but only intra- vitelline, albuminoid bodies. 



The stalked ovum exhibits on its surface and in relation to each of the 

 follicular cells, protrusions of the vitellus, especially marked in C. cinereus. 

 The summit of each vitelline expansion is in close association with the 

 nucleus of the follicular cell. Soon these protrusions retract, dragging 

 with them the nucleated portions of the several follicular cells. The stalk 

 degenerates, and before the final rupture is represented only by a mem- 

 branous shred. The point of rupture corresponds to the micropylar orifice. 

 The follicular membrane becomes thickened and depressed ; it ought not 

 to be spoken of as coque or chorion. The final non-cellular membrane, 

 described by Sabatier, does not exist. 



Nephridia and "Liver" of Patella vulgata.*— Dr. A. B. Griffiths has 

 made a chemical examination of the nephridia of the common limpet, and 

 has been able to isolate uric acid, and to obtain successfully the " murexide 

 test." He finds that, with regard to the " liver," its secretion converts 

 starch into glucose-sugar, as proved by the use of Fehling's solution ; the 

 secretion produces an emulsion with oils and fats, yielding subsequently 

 fatty acids and glycerol ; when a few drops of the secretion were examined 

 with chemical reagents under the Microscope a brown deposit was obtained 

 with a solution of iodine in potassium iodide ; with concentrated nitric acid 

 there was a yellow coloration, due to the formation of xantho-proteic acid ; 

 both these reactions show the presence of albumin in the secretion of this 

 organ. 



On the soluble ferment being isolated by the method of Wittich and 

 Kistiakowsky it was found to convert fibrin into leucin and tyrosin, no 

 glycocholic or taurocholic acid could be detected, and no glycogen was 

 found in the organ or its secretion ; but this secretion does contain leucin 

 and tyrosin. The author concludes, therefore, that the "liver" of the 

 limpet has a similar function to the pancreas of the Vertebrata. 



Morphology of Epipodium of Rhipidoglossate Gastropoda-f — M. P. 



Pelseneer, in consideration of the very various opinions that have been held 

 as to the morphology of the epipodium in rhipidoglossate Gasteropods, has 

 reinvestigated the anatomy of TrocJius. He finds that in it each pedal cord 

 has an external longitudinal groove, but it is, nevertheless, not composed of 

 two nerves, the peculiar conformation being due not to the fusion of two 

 difierent centres, but to the commencing separation of a single one ; this 

 specialization is due to the development of the epipodium. The pleural 

 ganglion lies at the commencement of the pedal cord, where the visceral 

 commissure commences to be formed. M. Pelseneer finds, therefore, that 

 the pedal cord of Trochus is single, and that the epipodium is a part of the 

 foot; it would, indeed, be hard to conclude otherwise, when we examine a 

 Trochus externally, for it may then be seen that the epipodium has no 



* Proc. Roy. Soc. Lond., xlii. (1887) pp. 392-4. 

 t Comptes Reridiis, cv. (.1887) pp. 578-80. 



1887. 3 Q 



