212 l>K. JAMES FOULIS. 



having round it a minute quantity of pioto[)lasm. The 

 stroma of tlie ovary of an adult cat has an exactly similar 

 structure. In the adult rabbit's ovary, in a single section- 

 we may find young ova in various stages of development. 

 In a very young ovum (fig. 15, m), we notice first the large 

 germinal vesicle, with its germinal spot. Around the 

 germinal vesicle is a small quantity of protoplasm, im- 

 mediately in contact with which are several small fusiforin 

 corpuscles {n, n). These lie flattened against the ovum round 

 its yelk, and are exactly similar to tlie fusiform corpuscles 

 of which the stroma {j) is composed. Around an ovum 

 slightly farther advanced in growth we find one or two of 

 the fusiform corpuscles [n, n) have assumed a swollen con- 

 dition, and in some instances"individual corpuscles are in the 

 act of dividing. In the case of an ovum still farther ad- 

 vanced in development, the corpuscles round the yelk sub- 

 stance liave now assumed a spherical form, and as they 

 increase in number and press against each other, they 

 gradually become columnar (fig. 17, r). 



As in the case of the human foetal ovary of seven and a half 

 months, the corpuscles of the membrana granulosa thus formed 

 consist of vesicular nuclei placed close together, their walls 

 being almost in contact, but a very minute quantity of cement 

 material lying between them. When this young membrana 

 granulosa is looked down upon from above, the corpuscles 

 present a beautiful pavemented appearance. The nucleus of 

 each corpuscle is polygonal from pressure by its neighbours 

 (fig. 18, r). By the constant division of the corpuscles, the 

 membrana granulosa soon consists of several layers (fig. 19, 

 r), and a follicular space is formed by the breaking down and 

 solution of some of the corpuscles. In the nearly ripe 

 Graafian follicle of the rabbit's ovary one frequently finds 

 several small follicular spaces in different parts of the thick 

 membrana granulosa; and in a section made through such a 

 follicle, bands or straps of membrana granulosa cells appear 

 to pass from the ovum to the wall of the follicle. These 

 bauds were called " Hetinacula " by Martin Barry. They 

 are simply appearances produced when the section has passed 

 through the walls or septa which separate several follicular 

 spaces lying near each other. 



In the ovary of the adult or old cat (fig. 21), we can trace 

 in a beautiful manner the growth of the corpuscles of the 

 membrana granulosa from the fusiform corpuscles of the 

 stroma, which lie next to the protoplasm or yelk of the im- 

 bedded young eggs. In a section, we have first the epithe- 

 lium on the surface. This consists of small fiat polygonal 



