MORPHOGENESIS OF THE MAMMALIAN OVARY 369 



follicles so shown, enlarged drawings are given in figures 29 and 

 30; figure 29 may be compared to the sectional view shown in fig- 

 ure 23 and figure 30 may be similarly compared with figure 18. 

 Within the larger masses an o\Tjm was contained completely en- 

 closed. The picture that is afforded by the reconstruction sup- 

 ports, I believe, the evidence which the histology furnishes, name- 

 ly, that in most instances the process illustrated by these peculiar 

 follicle formations is one of inclusion rather than of exclusion of 

 the ovum, in most instances at least. 



Observations of these formations by earlier workers than von 

 Winiwarter and Sainmont in the cat's ovary, or similar structures 

 in the ovaries of other animals, appear to be lacking, von Kolli- 

 ker, it is true, and Biihler in his earlier work, regarded the follic- 

 ular epithehum as coming from the medullary cords and these 

 in turn from the mesonephros, investing the egg cells (which were 

 derived from the germinal epithelium) by growing around them, 

 so that relations similar to those met with in the kitten's ovary 

 may have been influential in forming their interpretations. But 

 neither their description nor figures give us definite evidence. 



The fate of these peculiar follicles is one of considerable impor- 

 tance in their interpretation. While many of these follicles evi- 

 dently degenerate, the majority I believe remain as the large irreg- 

 ular, usually pluri-ovular follicles which are found in the ovaries 

 of kittens before the onset of sexual maturity. Such follicles are 

 shown in figure 13 and were figured by Sainmont (fig. 15) in his 

 earlier paper, wherein they were not specifically discussed, al- 

 though they were obviously thought of as derived from the ''egg 

 tubes of Pfliiger. " In the later and larger work with von Wini- 

 warter, so often referred to in this paper, these follicles were de- 

 scribed and regarded as developed out of the material of the 

 second proliferation (Pfliiger's egg tubes), succeeding as a second 

 set the 'medullary follicles' formed from the medullary cords of 

 the first proliferation which entirely degenerated. This inter- 

 pretation is a necessary corollary to the interpretation given by 

 them of the peculiar follicle formation with which we have just 

 been dealing. Figures showing the irregularity and pluri-ovular 

 character of these follicles are given (11 text figures, p. 90) but none 



