RIDDLE: ANIMAL HORMONES 97 



nite. Estrone produces localized growth in oviduct, mammary glands and 

 uterus. It reduces or suppresses the output of the pituitary hormone, gonado- 

 trophin. It affects bone development and general bodily form in some species. 

 It has an action on the calcium, phosphorus and fat of the blood. In the mental 

 sphere it affects sex behavior. 



The past 15 years of study of the actions, interactions and automatic con- 

 trol of release of the pituitary hormones in the bodies of higher animals have 

 provided a purely natural basis for some of the most mysterious performances 

 and adjustments of our own bodies. Now, for the first time in the long history 

 of man, human beings partly know a series of organs and substances which — 

 acting in high degree as a self-regulating system — largely control the fuller 

 expression of growth, the rhythms of reproduction, and some aspects of tem- 

 perament and behavior. In short, we have come to recognize our anterior 

 pituitary gland as the master or governing gland ; also, the brain and this 

 master gland are now marked as the two truly basic sources of the strength 

 and competence of man. It should arouse biologist and layman alike to reflect 

 that up to our own time mankind has made its whole history — its conquests, 

 its arts, its literature, its laws, its religions, its philosophies — while wholly 

 ignorant of one of the two physical sources from which the abilities of an 

 individual human being are derived. 



Carnegie Institution of Washington 



Department of Genetics 



Cold Spring Harbor, New York 



