148 THE DUCTLESS GLANDS 



as fast as its fellows which had not been touched. The animal 

 was killed when five months old, and no discoloration of the 

 skin or hair could be detected. The lumbar and other 

 lymphatic glands were found enlarged. 1 Commenting upon 

 this, Sir Edward Schafer says : " The rat happens to be the 

 one common animal which is able to withstand complete 

 removal of both suprarenal capsules. The reason for this 

 was not at the time apparent, although it is now known, for 

 the rat is exceptional in possessing in various parts of the back 

 of the abdomen and pelvis numerous small glandular structures 

 which are composed of cells having the same characteristic 

 features and functions as the cells of the suprarenal medulla." 



But all observers have not been successful in keeping rats 

 alive after double adrenal extirpation. Thus, H. and A. 

 Cristiani found that in their experiments, unless a little of the 

 medullary substance were left behind, the rats always died. 

 From these experiments we should be justified in concluding 

 that it is the chromaphil tissue (including the medulla of the 

 adrenal body) which is essential to life. But, as we have 

 already seen, Wiesel arrived at a different conclusion viz., . 

 that it is the survival of accessory cortical substance which 

 saves the animal's life. We thus see that the experimental 

 evidence as to the effects of extirpation of the adrenals in the 

 rat is somewhat conflicting, and the explanations offered by 

 different observers as to the occasional or frequent absence 

 of ill effects after extirpation are also conflicting. Moreover, 

 it does not appear to be the case that the rat is more richly 

 endowed with extracapsular chromaphil cells than are other 

 common animals. The present writer has been so far totally 

 unable to demonstrate any such tissue by the method of 

 Stilling and Kohn, and is further informed by Dr. Kohn that 

 there is, at any rate, no essential difference between the rat 

 and other animals as regards its chromaphil tissues. 



Vassale, who has performed a series of experiments with 

 full knowledge of the anatomy of the chromaphil cells and 

 their distribution in different animals, points out that the 

 " paraganglion abdominale aorticum " is the most important 

 mass of chromaphil tissue outside the adrenal body, and that 



1 This description is taken from the catalogue of the museum of University 

 College Hospital, whence the specimen was borrowed by Sir Edward Schafer 

 for the purpose of his lecture. 



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