THE ENDOCRINE ORGANS, OR DUCTLESS GLANDS 733 



gland. Our investigations must concern the effect of removal of the 

 whole gland or of the injection of extracts of it, and as we proceed to 

 examine the data, it will become evident that most of the effects ob- 

 served to occur as a result of injection of extracts of the gland, can 

 be attributed to the medulla. The fatal effects of complete extirpation, 

 on the other hand, are probably due to removal of the center. 



Adrenalectomy 



Excision of the adrenal gland in most animals is very quickly fatal, 

 the only well-known exception being in the case of the white rat, in which 

 excision of both adrenals may not be incompatible with life. For some 

 time after recovery from the anesthetic the animal upon which double 

 adrenalectomy has been performed usually behaves in a perfectly normal 

 fashion, although it may be less lively and less inclined to feed than 

 usual. Very soon, however, generally within twenty-four or forty- 

 eight hours, definite symptoms of muscular weakness are apparent. This 

 weakness soon becomes extreme, and is accompanied by a feeble pulse, 

 a depression of body temperature, and, later, by dyspnea. After an 

 interval which is never longer than a few days, death supervenes, being 

 sometimes preceded by convulsions. 



When only one adrenal is removed, very few animals succumb; and 

 if some time is allowed to elapse so that the immediate shock of the 

 operation has disappeared, it will usually be found that removal of the 

 remaining adrenal, although ultimately fatal, is not so quickly so as 

 when both glands are removed at one operation. The reason for this 

 result is that opportunity is given for a compensatory hypertrophy of 

 accessory adrenal bodies to occur. Such accessory adrenal bodies may 

 be composed of cortical or medullary tissue, and there is a growing belief 

 that the cortical tissue is the more important. Chromaffin tissue is found 

 in most animals along the front of the aorta, between the renal arteries, 

 where it can usually be recognized by staining the tissue with chromic acid. 

 Sometimes accessory chromaffin tissue is located in distant parts, 

 as in the epididymis of the rat, for example. It is said that life can 

 be maintained if one-eighth of the total amount of the adrenal substance 

 be present in the body. Attempts to prolong life after adrenalectomy 

 by adrenal transplantation have almost invariably met with negative 

 results, because the graft undergoes a rapid process of necrosis and dis- 

 appears; although it is said that transplantation may sometimes be suc- 

 cessfully accomplished if the grafting is done into the kidney. Adminis- 

 tration of suprarenal extract is also without definite benefit after 

 adrenalectomy. . 



