A HORMONE FOR GESTATION 



many details of the chemical manipulation. After various 

 tribulations, one of which I shall narrate below (page 118), 

 we found (1929) that we could obtain a crude oily extract, 

 looking like a poor grade of automobile grease, which when 

 injected into experimental rabbits was a perfect substitute 

 for their own ovaries in tests such as described above. After 

 5 days' injection, progestational proliferation was complete. 

 This is well illustrated by comparison of Figures C and D 

 on Plate XVIII, which show sections of the uterus of a cas- 

 trated rabbit before and after treatment. 



In some of our experiments, in which a large dose was used, 

 we even improved upon nature by producing more extensive 

 progestational proliferation than normally occurs. What was 

 even more striking, the embryos at 6 days were just as well off 

 as if their mother's own ovaries had seen to their welfare. 

 Plate XVIII, F shows two such litters of embryos 6 days old, 

 in rabbits castrated more than 5 days before. Evidently our 

 crude oily extract contained the long-sought hormone. 



At the University of W^isconsin, at the same time, F. L. 

 Hisaw and his associates, Meyer, Weichert and Fevold, were 

 also engaged in the extraction of sows' ovaries in the search 

 for an active substance. Their reason for looking for a hor- 

 mone was, however, curiously different. In the pregnant 

 guinea pig, as the time of birth approaches, the two pelvic 

 bones, right and left, become separated where they join in 

 front ; that is, on the belly side of the animal. The bony junc- 

 tion in fact almost melts away, in order to allow birth of the 

 infant guinea pigs, which are so large in proportion to the 

 mother that they cannot pass through the pelvis as it nor- 

 mally exists. This is one of the strangest of those strange 

 adaptations which make the reproductive functions of one 

 species different from those of another, and which puzzle and 

 confuse the investigator, but sometimes offer unexpected clues 

 if he is sharp enough to see them. 



Looking for the cause of this pelvic relaxation in the 



{ 113 } 



