THE SUPRARENAL SYSTEM 139 



pression of both suprarenals, provided that they are destroyed 

 separately, several weeks being allowed to elapse between the two 

 operations. 



From the results of his experiments with dogs and rabbits, 

 ^Tizzoni came to the conclusion that the destruction of one or both 

 suprarenals is followed by death. He believed that death may 

 occur soon after operation or that it may be postponed for weeks 

 and even months, and that it occurs as the result of serious changes 

 of the central and peripheral nervous systems. He describes far- 

 reaching disturbances of the nerve-fibres and ganglion-cells, 

 accompanied by pronounced congestion, changes in the vessel 

 walls, haemorrhages, and leucocyte infiltration into all parts of 

 the nervous system. Tizzoni's experiments do not prove that the 

 suprarenals are essential to life, for his animals sometimes sur- 

 vived experiment for months and even years. Moreover, 

 definite proof of a relationship between the operative procedure 

 and the post-mortem findings would have to be forthcoming. 

 Such proof is lacking; and, in view of the method of operation 

 employed, by which total extirpation of the suprarenals has rarely 

 been accomplished, Tizzoni's experiments seem rather to show 

 that animals with even serious lesion of the suprarenals may live 

 for a long time without pathological signs, provided that these 

 organs are not entirely destroyed. 



Tizzoni's statement that, whether one suprarenal or both were 

 extirpated and, in the latter case, whether they were removed 

 together or singly, the results were in all cases the same, is a 

 proof of the unreliability of his conclusions. This statement 

 was challenged by H. Stilling in 1890. Stilling found that 

 young rabbits, in which the left suprarenal had been destroyed, 

 lived for several months to over a year without showing signs of 

 disturbance. 



Stilling was able to show that, after extirpation of the one 

 suprarenal, the other became very much larger, and in fact 

 showed compensatory hypertrophy. This is a discovery of the 

 greatest importance in determining the functional significance of 

 the suprarenals. 



According to Stilling, the weight of both suprarenals in the 

 rabbit is on an average o.i grm. to 1,000 grm. of body 

 weight, but after extirpation of the left gland he found that in 

 six cases the right gland weighed 0.17 to 0.43 grm. per kilo of 

 body weight. He also found that after the removal of both supra- 

 renals, the remnants of tissue which it is almost impossible to 

 avoid leaving upon the right side, may by proliferation of the 

 undamaged cells, become as large as the normal suprarenal. 

 Stilling, like Canalis, found accessory suprarenals in normal rab- 

 bits in two cases out of forty, and in every case where the principal 

 organs had been removed; he makes the interesting statement 

 that, after extirpation of one suprarenal, accessory suprarenals are 



