6 4 



FRANK R. LILLIE. 



with the utmost care as to sizes and proportions of the parts. The 

 much smaller size of the gonads of the free-martin is apparent at 

 a glance. The actual measurements giving the average of the two 

 sides in each case are: free-martin — 1.727 mm. X 0.818 mm.; 



Fig. 7. Internal urinogenital organs of free-martin No. 62. 3.75 cm. great- 

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

 Miillerian duct; 5. Wolffian duct; 6. Allantois ; 7. Umbilical artery; 8. Ho- 

 mologue of scrotal sac of male; 9. Phallus; 10. Inguinal ligament ("round 

 ligament " of uterus). 



male twin — 2.622 mm. X 1-346 mm. ; normal female — 2.568 mm. 

 X 1-346 mm. The third dimension exhibits at least an equal dif- 

 ference, as may be seen by comparison of the outlines of cross- 

 sections, Fig. 10, a, b, c, drawn at identical magnifications. The 

 male and female normal controls may be regarded as typical for 

 size of- the gonads at this stage, for I have examined several other 



