1182 PHYSIOLOGY 



A study of the development of the suprarenal glands shows that we have 

 here to do with two distinct tissues, probably differing in the part they play 

 in the animal economy. Whereas the cortex is derived from that portion 

 of the mesoblast, the ' intermediate cell mass/ from which the mesonephros 

 is also developed, the medulla is produced by an outgrowth from the sym- 

 pathetic system and may be said indeed to consist of profoundly modified 

 nerve-cells. In many fishes these two elements of the suprarenal gland 

 remain separated throughout life, the cortex being represented by a series 

 of paired interrenal bodies lying on the front of the spinal column, and the 

 medulla by a number of collections of chromafrine cells lying in close juxta- 

 position to the spinal nerves. In some animals accessory suprarenals are 

 not infrequent in which both cortex and medulla may be represented. In 

 all animals we find masses of tissue, the so-called paraganglia, in close associa- 

 tion with the sympathetic system, which present the chromafrine reaction 

 typical of the medulla. Since a watery extract or decoction of these bodies 

 has the same influence on injection into the blood-stream as an infusion of 

 the medulla of the suprarenal body itself, we are probably justified in 

 regarding these bodies as equivalent to accessory medullary portions of the 

 suprarenal. They have the same origin, the same staining reactions, and 

 the same physiological effect as the latter. 



The functions of the suprarenal bodies were a matter of pure hypothesis 

 before Addison in 1855 drew attention to the coincidence of degenerative 

 destruction of these bodies with a disease which has been known since that 

 time as Addison's disease. The three cardinal symptoms of this disorder 

 are (1) bronzing of the skin, (2) vomiting, (3) excessive muscular weakness 

 and prostration. The disease is almost invariably fatal. Addison's observa- 

 tions have been amply confirmed since that time, but we are not yet in a 

 position to account for the occurrence of all these symptoms as a result of 

 interference with the cortex and medulla of the suprarenals. The experi- 

 mental destruction or extirpation of these bodies has naturally been fre- 

 quently carried out. The operation always leads to the death of the 

 animal within twelve to twenty-four hours. Even when the destruction is 

 carried out by degrees it has been impossible to reproduce the bronzing 

 which is so characteristic of Addison's disease. The one symptom which 

 is observed as a result of the experimental extirpation is the excessive pros- 

 tration, which is attended with muscular weakness and a lowered blood 

 pressure. In a few cases it has been found possible to keep rats alive after 

 total extirpation of these organs, but this result is probably due to the 

 frequent presence in these animals of accessory suprarenals. 



Schafer and Oliver in 1894 found that a watery extract or decoction of 

 the suprarenal bodies, when injected into the circulation, caused a very great 

 rise of blood-pressure, brought about chiefly by constriction of all the blood- 

 vessels of the body. The active substance responsible for this rise was 

 limited entirely to the medulla, infusions of the cortex being without influence 

 on the blood-pressure. Later on Takamine succeeded in isolating the active 

 substance, to which he gave the name of adrenaline, and since that time 



