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granulosa. This is limited externally by the membrana propria and 

 around this again the stroma has formed the theca folliculi. 



Cavities appear in the membrana granulosa which run together, 

 increase in size and become filled with a fluid the liquor folliculi. 

 Thus a ripe follicle is produced. The ripe follicle is perfectly normal 

 with respect to its large cavity, membrana granulosa, retinacula and 

 discus i^roligerus which however encloses the two apposed ova (fig. 9). 



Throughout all these various stages the two egg-cells are always 

 touching one another over a large part of their area and there is no 

 indication that the follicular cells are able to get between them. It 

 is further noteworthy that in the ripe ova the thickness of the zona 

 pellucida does not vary from one part of the circumference to 

 another. 



Specimen B. 



In this case the ovary was not quite so well preserved, but 

 nevertheless it was possible to make out a fair amount of histological 

 detail. The animal from which it was taken had ovulated but a 

 short time previously and so the ovary contained corpora lutea in a 

 very early stage. It also contained a fair number of almost ripe 

 follicles some of which were biovular (fig. 2), The abnormality af- 

 fected a larger number of the follicles than in A, perhaps as many 

 as 20 per cent. Like the previous instance the follicles were in all 

 stages of growth and the ova contained in any one of them were 

 approximately equally developed and always closely apposed to one 

 another. The great point of difference was that in the ovary now 

 being considered the follicles contained a varying number of egg- 

 cells two (fig. 2 & 9), three (fig. 10) four (figs. 11 & 12) and even 

 five (figs. 11 & 12). Only biovular follicles were found among those 

 that were nearly ripe, but it is to be remembered that the majority 

 of the ripe ones had already burst. The ovules were apparently 

 normal, possessing well marked nuclei and nucleoli. 



The general account of the various stages of development of the 

 follicles given above will apply equally well in this female the only 

 difference being that the number of ova in one follicle varies. 



Again the zona pellucida was of the same thickness at all parts 

 of the circumference of the eggs. Here however, a larger portion 

 of the periphery of each ovum is contiguous with the neighbouring 

 ova and at no stage is there any indication that the follicular cells 

 could penetrate between them. 



