150 INTERNAL SECRETION 



very frequently survive the removal of both suprarenals. This 

 shows that the remnants of tissue left in situ by Christian! have 

 no appreciable functional significance. A. Kohn, who emphasizes 

 the physiological importance of the chromaffine tissue and lays 

 special stress upon its importance to life, is inclined to doubt 

 the value of the last-mentioned experiments. He says : ' The 

 complete destruction of the medullary sjubstance is supposed to 

 cause death. But in many mammals, such as cats and rabbits, a 

 considerable quantity of chromaffine tissue lies externally of the 

 suprarenals upon the ventral surface of the abdominal aorta. 

 Why is it that these structures do not prevent death, if a small 

 portion of medullary tissue when left in situ is able to do so?" 

 According to Kohn, it is even more difficult to reconcile this 

 view with the results of experiments on amphibia. " In the 

 amphibia, the amount of extracapsular chromaffine tissue in the 

 sympathetic is considerably in excess of the medullary substance, 

 and yet after complete destruction of the suprarenals, frogs and 

 newts (tritons) invariably die. How is it that the large amount 

 of extracapsular chromaffine tissue which remains after operation, 

 does not prevent the death of these animals, if a minute propor- 

 tion of suprarenal tissue, which may not even contain chromaffine 

 cells, is able to maintain life for many weeks?" My answer to 

 this question is : That the animals will survive without medullary 

 tissue, for, in the free portions of the adrenal system they possess 

 a sufficiency of extracapsular chromaffine tissue. If it were 

 possible to extirpate all the free portions of the adrenal system, 

 which is, of course, technically impracticable, then and then only 

 should we be justified in referring the death of the animal to 

 suppression of the function of this system. 



The specific activity and physiological significance of the 

 adrenal system, together with that of its subdivision, the supra- 

 renal medulla, cannot, in face of the evidence, be doubted. That 

 it is important and even essential to the life of the organism we 

 know, but the proof of this is not supplied by the results of 

 experimental extirpation. These experiments tend rather to show 

 that the cortex, or more correctly the interrenal tissue, is necessary 

 to the life of the animal. 



EXPERIMENTAL EXTIRPATION WITH FISH. 



During my stay at the zoological station at Naples, in 1899, 

 I undertook a series of experiments with the object of determining 

 the vital importance of the interrenal tissue in fish. The most 

 favourable conditions appeared to me to be provided by the topo- 

 graphically separate interrenal and adrenal organs of the Selachii. 

 I was compelled at the outset, however, to abandon all attempts 

 at extirpation of the adrenal system on account of its intimate 

 association with the cardinal veins. Even the first pair of large 



