68 BENJAMIN H. WILLIER 



diagram indicates that the sexual cords bear no definite orienta- 

 tion to the rete (r). 



Diagram A" represents an ovary at about the time of birth. 

 It differs from the ovary A' chiefly through the increase in size 

 of the cords of Pfliiger (p) and the retrogression of the medullary- 

 cord region. In the latter the medullary cords have mostly 

 degenerated; connective-tissue fibers (indicated by the area of 

 short dashes, ct) and blood-vessels have increased. The rete, 

 although distinct, is destined to degenerate in still older stages. 



Diagrams B, C, and D, on the other hand, illustrate three 

 steps in the transformation of an ovary of the indifferent stage 

 A into a free-martin gonad which is morphologically a testis. 

 Diagram B represents a low degree of transformation in the male 

 direction. The sex-cord region (sc) is comparatively small and 

 poorly organized. The arrangement of the dots in the stippled 

 area (sc) indicates that the sexual cords are irregularly arranged. 

 The rete (r) lies in its primitive position at the hilus, and has not 

 penetrated far into the sex-cord region (sc). It is important to 

 note that stage B resembles the indifferent stage A in possessing 

 homologous parts; however, stage B differs from stage A in the 

 absence of the germinal epithelium (ge) and the presence of a 

 tunica albuginea (to). It differs from stage A' in the absence 

 of the cortex (cords of Pfliiger, definitive albuginea, and germ- 

 inal epithelium), but resembles it in the irregular arrangement 

 of the sexual cords (sc), the absence of connections (tubuli recti) 

 between the sexual cords and the rete tubules, the position of 

 the blood-vessels and rete, and the presence of a tunica albuginea 

 (to). 



The next step in transformation is illustrated by diagram C, 

 and exhibits an increase in size and organization of the sex-cord 

 region (sc) ; establishment of connections (tubuli recti, st) between 

 the sexual cords (sc) and the rete tubules (r) on all sides of the 

 rete except the side adjacent to the tunica albuginea (to); and 

 the addition of a head of an epididymis (he), the tubules of which 

 are connected with the rete tubules (r). The sexual cords in 

 this stage of transformation are so arranged that they radiate 

 out from the straight tubules (st), as indicated in the diagram by 



