REGULATION OF GROWTH 



that growth is retarded. The protein phase of metabolism ap- 

 peared particularly to be reduced. The authors' dismissal of 

 the growth-promoting hormone as the important factor is 

 largely based on the greater effect of whole pituitary implants 

 in comparison with that of a growth-promoting extract 

 ("Antuitrin G"). However, the comparison was made under 

 different conditions as to the age of the rats and the duration 

 of zinc-deficiency. Therefore, until growth-promoting hor- 

 mone or other better-defined anterior pituitary hormones 

 have been clearly excluded, it is undesirable to identify a new 

 pituitary hormone on so slender a basis. 



The effect oj growth-promoting hormone on the growth of yteo- 

 plasms. — Engel (1935) has made further observations on the 

 relationship of the pituitary and of gonadotropic hormones 

 (prolan, gonadotropic hormone of pregnant-mare serum) to 

 the growth of transplants of EhrHch's adenocarcinoma in 

 mice. He concluded that gonadotropic hormones may have 

 some inhibiting effect on the growth of the tumor and that 

 pineal extract may have a marked inhibitory effect. He be- 

 lieved that the depressing effect of pineal extract is indirect 

 and due to a secretory inhibition of, or antagonism toward, 

 the growth-promoting hormone. Several recent authors 

 agree that hypophysectomy retards the growth of malignant 

 neoplasms, especially if transplantation is delayed several 

 weeks after operation (Walker mammary carcinoma: Sam- 

 uels and Ball, 1935; neoplasm due to i :2:5:6 dibenzanthra- 

 cene: Ball and Samuels, 1936; transplanted neoplasm: Reiss, 

 1936). Reiss found that the oxygen-consumption of such 

 tumors is low, but that aerobic glycolysis remains unchanged 

 or increases. Emge and Murphy (1936), investigating the 

 growth of autogenous sarcoma in the rat, observed no striking 

 effect of hypophysectomy on tumor-growth except when 

 transplantation was undertaken some time after operation. 

 They could detect no increased rate of tumor-growth as a re- 

 sult of the administration of growth-promoting extract to 

 tumor-bearing normal or hypophysectomized rats. Likewise 



[43] 



