NOTES AND MEMORANDA. 405 



3. Tlio ova are fertilized in the ovary. 



4. The kidney is a ramified gland, placed at the base of the 

 coelom, and invested by a ciliated epithelium ; it gives off a median 

 and unpaired efferent duct, which opens below the anus. 



5. The secreting vesicles of the renal organ are developed in the 

 nucleus of the kidney-cells, and not, as in most jMollusca, in the 

 protoplasm of these elementary parts. 



6. The muscular fibres form fibrillar bundles, which are enclosed 

 in a nucleated sarcolemma. 



7. These fibrillas are simple in the pedal muscles, but in those 

 which form the buccal mass there is an anisotropic substance which 

 forms sarcous elements, and these are separated from one another by 

 isotropic substance. The separate fibrillae do not correspond to one 

 another, so that the " striation " which has been observed in the same 

 region in the Gasteropoda cannot be said to exist here. 



It is of interest to observe that M. Jhering states that there are 

 striped or unstriped fibrilLne in the adductor muscles of the Ano- 

 donta, the portion which is striped ai)pearing to be that which effects 

 the rapid closure of the shell. 



The paper is illustrated by a plate of sixteen figures. 



Phenomena which precede the Segmentation of the Ovum in 

 Helix aspersa — M. Perez thus describes these phenomena in a paper 

 to the Bordeaux Society : * — The ovarian ova meet, in the diverticulum, 

 the spermatozoids which fecundate them. The germinal spot, at first 

 clear and homogeneous, assumes a cloudy aspect, and two small 

 nucleoli become vaguely visible. Later on, the spot becomes pale and 

 diffluent and the germinal vesicle disappears. 



Around the freed nucleoli a radial system is formed of the fusiform 

 body and the two suns (soleils) known to embryologists. The two 

 nucleoli enlarge, and soon acquire a vesicular envelope. It is not long 

 before they are divested of the radial system which they had formed 

 by the contractions of the vitelline mass, which pushes outwards 

 (under the form of polar globules) the radial substance, which is 

 more fluid than the vitellus. 



But the two cellular bodies thus enucleated remain in the vitellus, 

 where they are shown with the utmost ease by reagents in the place 

 formerly occupied by the germinal vesicle. They raj)idly increase in 

 size as they approach the centre of the vitellus ; and at the same 

 time their nucleus decomposes into a great number of nucleoles of 

 unequal size. Then one of them is completely destroyed. The other, 

 undergoing very nearly the same fate as the germinal vesicle, disap- 

 pears, leaving as its only trace two of the nucleoli which it enclosed. 

 These, becoming free by the destruction of the cell-wall, give rise to 

 a new radial system similar to the first, which becomes the " point de 

 depart " of the segmentation. 



Liver and Digestion of the Cephalopodous MoUusca. — From 

 experiments made by M. Jousset de Bellesme on the liquid secreted 

 by the liver of Octoims vulgaris, obtained by cutting a peri spherical 



* ' Eev. Intemat. Sci.,' iii. (1879) 280. 



