THE PITUITARY BODY 



5. The thymus. — If anterior pituitary tissue is fed to the 

 fowl, growth is inhibited and the thymus undergoes a more 

 rapid involution (Wulzen, 1914). Kemp (1934) injected a 

 growth-promoting extract into mice dwarfed because of a 

 hereditary defect of the pars glandularis. Growth in normal 

 proportions occurred in the body and all the organs except 

 the thymus, in which an unusually marked proliferation of 

 the parenchyma was observed. 



6. The epiphysis. — Engel (1934) concluded that alkaline 

 extracts of the human epiphysis antagonize the growth-pro- 

 moting effects of extracts of the pars glandularis of the ox. 

 This conclusion was based on experiments of a few days' 

 duration in the rat (assay-technique of van Dyke and Wallen- 

 Lawrence); the extract of 1-2 human epiphyses appeared to 

 prevent the weight-increasing effects of 2 g. of the fresh pars 

 glandularis of the ox. 



Experimental obesity and the growth-promoting hormone. — 

 Evans (1924) reported that the marked obesity which Smith 

 produced in rats, probably by injuring the hypothalamus, 

 was not affected by the repeated injection of the growth- 

 promoting hormone. 



Biochemical changes following the administration of the 

 growth-promoting hormone. — Although Evans and Long 

 (1922) were of the opinion that, following the injection of the 

 growth-promoting hormone into normal, growing rats, the 

 "Increase in weight results to a great extent from a storage of 

 fat, but is not solely due to this, ....," subsequent work 

 has shown that the amount of fat in the bodies of injected 

 rats is reduced. The accompanying table summarizes what is 

 known about the composition of the rat caused to grow at an 

 increased rate and for a longer period by means of repeated 

 injections of the growth-promoting hormone (see p. loi)." 



From their careful investigation, Lee and Schaffer conclud- 



" From the data of Schafer (1931); Bierring and Nielsen (19J2); and Lee and 

 SchafFer (1934). 



[ 100] 



