322 
PROFESSOR ARTHUR ROBINSON ON 
the cells, and it bears, therefore, a close structural resemblance to the primitive 
vitreous body of the eyeball. That such a reticulum is formed in the ferret is obvious, 
and I am inclined to think, judging from the photographs of Van der Stricht (40) 
and Sandes (35), that it may be found in bats and Dasyurus ; but my specimens of 
ovaries of dogs, cats, rabbits, guinea-pigs, mice, and rats, though prepared in the 
same manner as those of ferrets’ ovaries, do not show the reticulum in the same 
clear manner, and 1 am inclined to believe, therefore, that modifications of the 
process found in ferrets may be present in other animals. 
Secondary liquor folliculi. 
So far as I am aware, no one has drawn attention to the formation of the 
secondary liquor folliculi in ovarian follicles. There is no doubt in the case of 
the ferret that it is present, that it is formed more rapidly, and that it is of 
more fluid consistence than the primary liquor, and that it takes part in the 
final distension of the follicle which precedes the rupture. But although the 
formation of the secondary liquor appears to have escaped the attention of 
observers who have paid special attention to the development of ovarian follicles, 
some of the figures they have given to illustrate other points of follicular develop- 
ment indicate that the secondary liquor is formed in the ovarian follicles of other 
animals besides the ferret. Thus the figure which Longley (20) gives to illustrate 
the conditions of the cumulus region - of a normal follicle of the cat, just before 
rupture, depicts essentially the same details as are shown in follicles of the ferret 
at the same stage of development, and which are represented in the photographs 
which constitute figs. 18 and 20, PI. III. Further, RuSvSo’s photograph (fig. 6, 
pi. xxxiv) suggests that something of the same kind takes place at all events 
in some ovarian follicles of rabbits. Indeed, unless the process is one of fairly 
common occurrence it is difficult to account ' for the extrusion of the ovum and 
its corona from follicles, such as those of the human female, the sheep, the bat, 
and Dasyurus viverrinus, in which the cumulus oophorus is merely a more or less 
prominent rounded elevation of the general follicular epithelium ; for there seems 
to be no reason why the evacuation of the primary liquor, which does not disturb 
anything more than the superficial part of the stratum granulosum, should break 
up and displace the somewhat dense mass of cells which forms the primitive 
cumulus, though it might readily break down the retinaculse which maintain the 
cumulus in position in some of the follicles of rabbits and some other rodents. 
The Growth of Ovarian Follicles. 
For many years after Pfluger’s descriptions of the tubes and nests of cells, 
which are present in the ovaries of the female embryos of all mammals, became 
generally known, it was presumed that the ova and the follicle cells which sur- 
