RELATION TO OTHER ENDOCRINES 215 



animals is similar to that noted in hypophysectomized young 

 rats in which growth does not cease until sometime after opera- 

 tion. 



In Figure 12 are reproduced typical curves which show the 

 effects of administering the adrenal cortical hormone or the 

 growth hormone of the anterior pituitary body to rats whose 

 growth had been stunted by various procedures. The periods 

 of treatment extended for 20 successive days, each period of 

 treatment alternating with periods of an equal length of time 

 during which no treatment was administered. 



As shown in Figure 12, administration of the adrenal cortical 

 hormone is without the least effect on the growth of rats stunted 

 by chronic adrenal insufficiency or by hypophysectomy. On 

 the other hand, the administration of extracts of the anterior 

 lobe of the pituitary is accompanied by a remarkable growth 

 approximating or exceeding that observed in normal animals. 

 It may be concluded, therefore, that the cessation of growth in 

 animals maintained for long periods in chronic adrenal in- 

 sufficiency is not due to lack of the adrenal secretion but is due 

 to pituitary insufficiency induced secondarily by the adrenal 

 insufficiency. 



The reproductive function of animals in adrenal insufficiency 

 is in abeyance, as described in Chapter IX. In the rat, the 

 periods of diestrus may extend for months during chronic 

 adrenal insufficiency. However, in animals in which growth 

 has ceased for several months, spontaneous oestrus may still 

 occur at intervals of several months, compared to 4 to 7 days 

 for normal rats. The animals conceive and may rear a normal 

 litter. About half the animals die during either pregnancy or 

 lactation. In such animals there is no evidence of failure of 

 mammary function and the young are normally nourished. 

 Undoubtedly, the strain of pregnancy like other strains upon 

 the organism (excessive heat, cold, drugs such as histamine, 

 etc.) which are innocuous to normal animals cannot be borne 

 by animals in chronic insufficiency. In animals surviving the 



