RELATION TO OTHER ENDOCRINES 225 



ganism have been noted. Epinephrine injections do not 

 affect the estrus cycle of mice. 639 Attempts have been made to 

 find changes in the epinephrine content of the adrenals occur- 

 ring during pregnancy in order to attribute certain pathological 

 manifestations occurring in this condition to an hypothetical 

 hypo- or hyperadrenalinemia. These attempts have yielded 

 only conflictory and contestable results. 



Sex differences in the size of the adrenals have been repeat- 

 edly demonstrated, the gland in the female being somewhat 

 larger than in the male. In the rat, for example, Hatai and 

 Jackson 286 found the adrenals to be about 20 per cent larger per 

 unit of body weight in the newborn female as compared to the 

 male. This difference gradually disappears so that in a 20 to 

 40 gram rat the adrenal weights are the same in the two sexes. 

 Thereafter, however, the sex differentiation again appears and 

 the adrenals of a 300 gram female rat are almost twice as large 

 as those of an equal sized male. 



Cyclic changes in the size of the adrenal cortex coincident 

 with the oestrus cycle were first pointed out by Stilling. 595 

 Similar changes have been described by Anderson and Ken- 

 nedy 14 in the mouse. In doves, Riddle 521 described an adrenal 

 hypertrophy coincident with ovulation. In the male also 

 adrenal hypertrophy during rut has been described in rabbits, 

 squirrels, and amphibia. 695 



The reproductive cycle is accompanied by such profound 

 changes in the general activity of the body as a whole that 

 one need not attribute any specific importance to the changes 

 occurring in the adrenal cortex. Such changes may be looked 

 upon merely as a reflection of increased body activity requiring 

 among other things an hyperfunction of the adrenal cortex. 

 It is unnecessary to assume any more direct adreno-gonadal 

 relationship and hypothecate the changes in the adrenal to be 

 the prime instigators of the sexual activity. The same criti- 

 cism is applicable to the changes in the adrenal during preg- 

 nancy or after castration. It must be remembered that all 



