SUPPLEMENTARY NOTES ON TWINS IN CATTLE. 



65 



specimens of each sex between 3 and 4 cm. in length for compari- 

 son. The hormone of the male has thus already operated so as to 

 inhibit the growth of the gonad of the female to a very marked 

 extent. 



Fig. 8. Internal urinogenital organs of male twin No. 62. 4 cm. greatest 

 length, X 6. 1. Gonad; 2. Wolffian body; 3. Vena cava inferior; 4. Mullerian 

 duct; 5. Wolffian duct; 6. Allantois ; 7. Umbilical artery; 8. Scrotal sac; 9- 

 Phallus; 10. Inguinal ligament (part of gubernaculum). 



The inhibition in growth is accompanied also by inhibition of 

 the characteristic differentiation of the ovary, though apparently 

 not as yet, to any marked degree, by stimulation of the male 

 homologues in the ovary. In Figs. 11, 12, and 13 comparison is 

 made between the histological structure of segments of those parts 

 of the section outlines of Fig. 10 indicated by the reference num- 



