THE SUPRARENAL SYSTEM 149 



of the present day, belong exclusively to the interrenal system. 

 There is also undoubted proof that, after extirpation of the supra- 

 renals, this tissue undergoes compensatory hypertrophy. These 

 are the two points upon which 1 base my assumption that the 

 interrenal tissue has a vital significance in the economy of the 

 organism. 



In the course of my investigations into the question of the 

 amount of suprarenal tissue necessary to the maintenance of 

 existence, I found that mammals (rabbits and dogs) would live 

 with one-eighth, or less, of their suprarenal substance, provided 

 that the portion left behind was composed of cortical tissue. 

 Further experiment showed that, after removal of one suprarenal 

 in toto together with the medullary substance of the other, more 

 or less of the cortex being left in situ, the animal not only 

 continued to live, but showed no signs of pathological disturbance. 

 I found in one of five surviving rabbits two small accessory inter- 

 renal structures situated to the right of the vena cava. In a 

 number of other instances, the destruction of the medullary por- 

 tion, in so far as this was possible by operative means, was 

 entirely negative in its results ; but I have never succeeded in 

 keeping animals alive after removal of the cortex and preserva- 

 tion of the medulla, no matter how carefully the operation was 

 carried out. 



These results are not, however, confirmed by those of Vassale 

 and Zanfrognini (1902). They found that the complete destruc- 

 tion of the medulla was followed, in cats and rabbits, by death 

 in exactly the same way as total extirpation of both glands ; while, 

 after partial destruction of the medulla, the animals lived for 

 three weeks and then died, showing signs of pronounced cachexia. 

 This fatal termination was ascribed by these authors to the 

 absence of the medullary tissue, while in those cases where the 

 animals survived, they attribute the result to the presence of 

 extracapsular chromaffine bodies. 



H. and A. Christiani concluded from their experiments with 

 rats, that in the case of these animals very minute portions of 

 suprarenal tissue suffice to support life, always provided that the 

 remnant contains a sufficiency of sound medullary tissue. Larger 

 portions, if composed wholly of cortical substance, will not pre- 

 vent a fatal termination. 



Without a knowledge of the method of operation, it is very 

 difficult to judge of the value of the results obtained by Vassale 

 and Zanfrognini. The experiments of H. and A. Christiani, 

 though apparently free from objection, are of little value in the 

 present connection, owing to the fact that accessory interrenal 

 structures are frequently present, especially in the testicles, of 

 the species which they employed as subjects. Rats always 

 possess a large amount of interrenal tissue and in some recent 

 experiments I found that these animals, especially adult males, 



