THE GROWTH-PROMOTING HORMONE 



ministration is about 3 weeks, female rats gain more weight 

 and do so in greater numbers than do males (Evans and 

 Simpson; see Fig. 26). 



Smith (1927, 1930) has clearly shown that pituitary im- 

 plants or the injection of extracts of the anterior pitui- 

 tary promptly cause the hypophysectomized rat to resume 



PERCENTAGE DISTRIBUTION OF CAINS IN BODY WEIGHT 



DURING TWENTY DAY ADMINISTRATION WITH AQUCOU5 



ALKALINE EXTRACT OF ANTERIOR HYPOPHYSIS 



I 10% 



2 



< 



O S% 



GAIN IN BODV WEIGHT IN GRAMS 



f^iG. 26. — A comparison of the response of male and female rats to a growth- 

 promoting extract of the pars glandularis. From Evans and Simpson (1931). 



growth. In rats dwarfed because of hypophysectomy, the ad- 

 ministration of the growth-promoting hormone produces rel- 

 atively greater changes in the skeleton than is the case in nor- 

 mal rats receiving the hormone. Pituitary implants do not 

 cause a greater change in weight and size than does the ad- 

 ministration of a crude extract of the pars glandularis of the 

 ox. Implants, however, do correct the atrophic changes in 



