360 



is described as originating from ingrowths of both the theca interna 

 and the theca externa, viz., by Honore in the rabbit (9), by Marshall 

 in the sheep (11) and by Volker in the marmot (26). On the other 

 hand it has been stated to be derived entirely from sprouts of the 

 theca interna^ by Sobotta in the mouse (21), by Stratz in Tupaja, 

 Sorea and Tarsius (24) and by van der Stricht in Vesperugo (25). 

 In D. viverrinus however, as we have already seen, the theca of the 

 ripe follicle is not differentiated into interna and externa layers and 

 the whole of the theca folliculi takes part in the formation of the 

 corpus luteum in the process of which it is almost entirely used up. 

 To sum up then, the corpus, luteum in the non-pregnant D. 

 viverrinus is derived from two sources. 



a) Its characteristic lutein cells are derived from the cells of the 

 cells of the membrana granulosa, by hypertrophy unaccom- 

 panied by direct or indirect cell division. 



b) The connective tissue network is derived from the ingrowths 

 of the theca folliculi which, in the ripe follicle, is not differen- 

 tiated into theca interna and externa and these thecal 

 ingrowths are accompanied by small blood vessels. 



Eurther at no stage is it possible to distinguish between the 

 corpus ]uteum of the non-pregnant female, i. e., corpus luteum spurium 

 and that of the pregnant female, i. e., corpus luteum verum. 



Polyovular follicles in Dasyurus. 



In the course of examining the ovaries in the foregoing investi- 

 gation one of them, viz. No. 7, was found to possess follicles con- 

 taining more than one ovum. Professor J. P. Hill had also en- 

 countered a similar abnormality in an ovary of D. viverrinus in the 

 course of his researches and this he has kindly handed over to me 

 for examination. The discovery of these two ovaries lead to a careful 

 search through the sections used in previous enquiry, those cut by 

 Dr. Sandes and those cut by Professor Hill amounting in all to 

 ovaries from forty-five animals. No further examples of this anomaly 

 were discovered. 



1 Marshall in his book (13) cites Dasyurus as one of the animals in 

 which the connective tissue network is "derived from the theca interna 

 alone". Whereas what Sandes quite correctly said was that it was "quite 

 impossible to distinguish between the part played bj^ the theca externa and 

 the rudimentary theca interna". 



