Contributions to the Sfiidy of the Oogenesis of Patella. 5 



cesophageal pouches, iUid often extends across the median line 

 towards the right side." At different seasons of tlie year the ovary 

 varies considerably in size, and it seems peculiarly liable to over- 

 growth. Ova are extruded by rupture of the ovary wall into the 

 cavity of the right kidney wlience they pass to the exterior. There 

 are no accessory sexual organs. 



The breeding season is in the autumn. Boutain found sexual 

 maturity to be reached in September at Eoscoff, but Davis and 

 Fleur regard it as somewhat later at Aberystwyth (/). 



NUTKITION OF THE YoUNG OoCYTES. 



Fig. 1, Plate I, shows a portion of one of the trabecuhe of the 

 ovary, lu the middle is the connective tissue basis, the cells of 

 which do not show at all clearly in Flemming-withovit-acetic prepa- 

 rations stained with iron alum haimatoxylin ; but with fixatives 

 containing acetic acid, and iu ethyl l)lue staining, the trabecula is 

 seen to be composed of rather long narrow cells witli elongated 

 nuclei, bound together by connective tissue fibres. On either side 

 of the partition thus formed are attached the undifferentiated cells 

 of the germinal epithelium with characteristic elongated nuclei, 

 the young developing oocytes and numerous yolk containing nurse 

 cells. At ()C. is seen a cell which has just commenced to differ- 

 entiate and acquire the characteristics of an oocyte. Its cytoplasm 

 is stained differently from that of the neighbouring cells, and it 

 contains several black granules. Similar cells of Mann-Kopscli 

 preparations show a concentrated Golgi apparatus, as in fig. 2. 

 With the F.W.A. and iron hematoxylin technique the cytoplasm 

 of the young oocytes stains a blue colour, while that of the neigh- 

 bouring cells is almost colourless. This difference in staining 

 properties seems t(j be due to the very active metabolism in the 

 cytoplasm at this stage, when the cell is preparing for growth, as 

 with its subsequent enlargement the cytoplasm stains a pale colour. 



During the primary >;tages of growth the young oocyte, attached 

 to the trabecula, is surrounded by nurse cells containing yolk 

 granules. As it grows out into the lumen of the ovary certain of 

 the yolk cells separate from the connective tissue of the trabecula 

 and come to surround it, forming a temporary follicle, as is seen in 

 the cell OV. At first these " follicle " cells contain numerous 

 yolk granules, but they are evidently used up in providing nourish- 

 ment' for the developing egg, for in oocytes which have just 

 separated off from the trabecula and come to lie freely in the 

 lumen, nurse cells are found surrounding them, as in fig. 13, but 

 in such cases it is not usual to find much yolk. It would seem 

 probable that this substance has been acted upon by enzymes and 

 become converted into a liquid which can be absorbed through the 

 wall of the oocyte. As the oocyte continues development the yolk 



