70 BENJAMIN H. WILLIER 



will furnish additional information concerning how complete 

 the transformation of a zygotically determined female into a 

 male individual by the action of male sex hormones is possible. 

 It will also furnish a positive demonstration of the existence of 

 'sexual dimorphism' in the sex glands of mammals; that is, for 

 the theory that the primordium of the mammalian gonad has the 

 potentialities for the development of both ovary and testis. 



A. Gonads having a low degree of transformation 



The reproductive glands belonging to this group are the least 

 modified of any in the series, yet they show the majority of the 

 typical male structures. They are characterized by their 

 undescended or ovarian position, by the absence of an epididy- 

 mis, and by the small size and low degree of organization of 

 the sex-cord region. The rete is comparatively large and well 

 differentiated. 



The histories of the two specimens which belong to this group 

 are detailed as follows: 



Case H-36. Born co-twin to potent bull. A Holstein free- 

 martin aged approximately two and a half years when killed, 

 December 15, 1916. External genitalia typically female. 

 Uterus rudimentary. Small gonads located an normal ovarian 

 position. Rudimentary spermatic cord; poorly developed sem- 

 inal vesicles enter the vasa deferentia. Only the posterior 

 portion of the vasa deferentia developed. 



Case H-40 (fig. 2) . Born co-twin to normal bull. Three years 

 old when slaughtered, February 3, 1917. External genitalia 

 female, but smaller than normal. Vagina rudimentary; uterus 

 absent. Wolffian ducts well developed, but made no connec- 

 tions with the gonads. Gonads in ovarian position. A plexus 

 of blood-vessels was attached to the anterior border of each 

 gonad. Seminal vesicles enter vasa deferentia (Wolffian ducts). 

 The tunica alhuginea and tunica vasculosa. Owing to poor 

 preservation, the gonad of H-36 will be only briefly described. 

 It is covered with a thick capsule of densely arranged connective- 

 tissue fibers, the tunica albuginea, as in the normal testis. Imme- 



