146 INTERNAL SECRETION 



(4) In certain exceptional cases, where animals have survived 

 the extirpation of both suprarenals and where the result is not due 

 to imperfect extirpation, it arises from special anatomical con- 

 ditions. In some animal species, as the dog and cat, such excep- 

 tional cases are extremely rare; in others, as in the rabbit, they 

 are of more frequent occurrence ; in rats, they are rather frequent, 

 and extremely rare in the case of guinea-pigs. In these cases the 

 survival of the animals is doubtless connected \vith the presence 

 of accessory organs. 



These structures are very rare in dogs and cats ; they occur 

 in about 15 to 20 per cent, of rabbits; in nearly 50 per cent, of 

 rates; in guinea-pigs, at the most, 4 per cent. 



(5) Partial destruction of the suprarenals, either by the removal 

 of one and large portions of the other, or by partial destruction 

 of equal portions of both, may be borne without results, or it 

 may cause death. Survival depends, in the first instance, upon 

 the amount of tissue destroyed. 



Repeated experiments have been made with the object of 

 discovering the amount of suprarenal substance necessary to life. 

 Mathematically precise results were hardly to be expected. 

 Langlois found that, in the case of rabbits and dogs, one-sixth to> 

 one-eleventh of the total weight was sufficient. I myself found 

 that cats, rabbits, and dogs always survived if, after the removal 

 of one suprarenal, one-quarter of the second was left in situ 

 that is to say, one-eighth of the whole amount of suprarenal sub- 

 stance. In isolated cases even smaller quantities sufficed. H. 

 and A. Christiani found that, in the case of rats, the extirpation 

 of one suprarenal together with half of the other, \vas born& 

 without ill-effects. If more than half of the second suprarenal 

 was removed, they found that some animals survived, while others 

 died. These authors are of the opinion that a very small quantity, 

 less than one-quarter of the total weight, of suprarenal tissue may 

 suffice to support life. 



THE RESULTS OF THE EXTIRPATION OF THE 

 CORTICAL AND MEDULLARY SUBSTANCES. 



I found in the course of my experiments that partial supra- 

 renal extirpation was followed by certain phenomena, which led 

 me to the conclusion that the amount of tissue left in situ is not 

 the only factor of importance, but that the part of the organ from 

 which the remnant is derived is also of considerable significance. 

 Experiments undertaken with the object of determining whether 

 or not the suprarenals as homogeneous organs are necessary to 

 animal life, served also to determine the significance of the 

 different parts and the vital importance of the interrenal and 

 adrenal systems. 



The question as to whether it was the cortex or the medulla 



