
IN MAN AND OTHER MAMMALIA. 369 
ment, the corpuscles round the yelk substance have now assumed a spherical 
form, and as they increase in number and press against each other, they gradu- 
ally become columnar (fig. 35, 7). 
As in the case of the human fcetal ovary of 74 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. 36, 7). By the constant division of the corpuscles, the mem- 
brana granulosa soon consists of several layers (fig. 37, 7), 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 granu- 
losa; and in asection 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 
bands were called “ Retinacula” by Martin Barry. They are simply appear- 
ances 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. 39), we can trace in a beautiful 
manner the growth of the corpuscles of the membrana granulosa from the fusi- 
form corpuscles of the stroma, which lie next to the protoplasm or yelk of the 
imbedded young eggs. Ina section, we have first the epithelium on the surface. 
This consists of small flat polygonal nucleated cells (fig. 40, 2,), about s_5oth or 
yoth part of an inch in diameter. This layer of epithelium is all that remains 
of the germ epithelium, and it can be stripped off from the ovary without 
difficulty. Below the epithelium, and passing round the ovary, is a stratum of 
connective tissue, consisting of elongated fusiform corpuscles. In the lower 
part of this stratum the fibres decussate freely. Immediately below this layer 
we come upon the remains of the large egg clusters which we described in the 
young kitten’s ovary. A perfect zone, consisting of young eggs, lies immediately 
under the stratum of tissue which passes horizontally round the ovary, under 
the epithelium. In this zone the eggs lie very close together, many of them are 
in actual contact. In each egg we recognise the central germinal vesicle, with 
its spot or nucleolus—the germinal vesicles are all about the same size. Below 
this zone of eggs is the general stroma of the ovary, processes of which consist- 
ing of elongated fusiform corpuscles and fibres, grow in between and around all 
the eggs in the egg zone. These processes of stroma then become continuous 
with the horizontal zone of tissue which lies external-to the egg zone, and with 
it grow round the ovary to form the tunica albuginea. As the processes of the 
stroma of the ovary grow in between and around the young eggs in the egg 
VOL, XXVII. PART III. 5D 
