ILLUSTRATIONS 



OVARIAN TRANSPLANTATION (Plate IV) 



(p. Ill) . . . . ... . Frontispiece 



From photographs in the possession of Professor 

 W. E. Castle. 



FEMINIZED GUINEA-PIGS (Plate I) ... 52 



By courtesy of Professor E. Steinach. 



MENDELIAN INHERITANCE (Plate II) . . . 86 



From photographs in the possession of Professor 

 W. E. Castle. 



UNIT CHARACTERS (Plate III) . .'.. ... 92 

 From photographs in the possession of Professor 

 W. E. Castle. 



