58 BENNET M. ALLEN. 



meet evaginations from the capsules of Bowman, with which they 

 fuse. Such evaginations are irregular in number, as many as 

 three having been counted upon the same glomerulus. Some 

 glomeruli may send out none at all. The tubuli recti connecting 

 the rete-cords with the seminiferous tubules are likewise irregular 

 in number, being apparently called forth wherever needed. 



Seminiferous tubules, medullary-cords, and rete-cords are 

 homologous structures. Not only are they of similar origin, but 

 their component cells show similarities. Two kinds of cells are 

 found in all three structures : (i) primitive sex cells, which have 

 already been described ; (2) cells more or less variable but 

 agreeing with one another in not having clearly marked cell 

 limits, and also in the absence of centrosphere and centrosome. 

 The cells of this second class form the germinative cells of the 

 seminiferous tubules, the follicular cells of the medullary-cords, 

 and the rete cells proper of the rete-tubules. 



Returning to the subject of the ovary, the peritoneum at the 

 time of separation of the medullary-cords, contains no differen- 

 tiated sex cells. ' Such may exist, but they are at all events in- 

 distinguishable from the remaining peritoneal cells. The peri- 

 toneum or germinal epithelium, as it may now be termed, next 

 begins to give rise to the cords of Pfliiger, which branch and 

 anastomose in a similar manner to the medullary-cords. Some 

 of these cords of Pfliiger may contain a well-defined lumen, in 

 the case of advanced embryos of the pig (15 cm. length). In 

 these later stages the inner ends of the cords are broken up to 

 form follicles. Follicles are likewise formed in medullary-cords. 

 These however, have nevermore than one layer of follicular cells 

 in the forms studied. 



The rete-cords come in contact with the medullary-cords, and 

 are then scarcely distinguishable from the latter in the case of 

 the rabbit. They contain no sex cells in later stages of the 

 ovary of that animal, although such are present in the rete 

 tissue when it is first laid down. By this criterion alone can 

 one, in a very general way, distinguish between medullary-cords 

 and rete-tissue lying within the rabbit's ovary. In the pig, on 

 the other hand, the rete-tissue shows some very interesting 

 characteristics. The portions of the rete-cords lying within the 



