ON THE PHYSIOLOGICAL PROPERTIES OF THE 

 GONADS AS CONTROLLERS OF SOMATIC AND 

 PSYCHICAL CHARACTERISTICS: V. THE EFFECTS 

 OF GONADECTOMY IN THE GUINEA PIG, ON 

 GROWTH, BONE LENGTHS, AND WEIGHT OF OR- 

 GANS OF INTERNAL SECRETION. 



CARL RICHARD MOORE, 

 THE UNIVERSITY OF CHICAGO. HULL ZOOLOGICAL LABORATORIES. 



To be able to interpret correctly the changes in weight of an 

 animal incident to experimental modification of the sex-gland 

 conditions, such as total castration or spaying followed by sex- 

 gland transplantations, it is necessary to know the relationship of 

 the weight of the normal to the totally castrated and totally spayed 

 animal. Certain investigators have employed relative weights of 

 the rat and guinea pig as indications of modification of the sexual 

 conditions (see Steinach and Holznecht), and certainly the reac- 

 tions of the guinea pig, in this respect, are not sufficiently under- 

 stood to justify such conclusions as have been announced. 



Steinach takes for granted that, inasmuch as the male of both ' 

 rats and guinea pigs is usually heavier than the female, the testis 

 is responsible for an internal secretion liberated by the interstitial 

 cells that promotes growth and otherwise leads to the production 

 of maleness, whereas the ovary is responsible for a secretion that 

 acts to retard growth. Acting upon this assumption, he utilizes 

 the weight of an animal at practically any age to compare with a 

 brother or sister animal to show the differential effects of sex- 

 gland grafts. 



In 1919 the writer called attention to the work of Stotsenburg 

 ('09, '13) on the rat wherein the growth curve was shown to be 

 independent of the testis, but the growth curve of females was 

 reduced by the presence of the ovary i,.e., totally spayed female 

 growth curves were from 17 per cent, to 30 per cent, higher than 

 that of their normal sisters. It is to be understood, therefore, for 

 the rat, that relative weight increase in a spayed female bearing a 



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