582 INTERNAL SECRETION 



the latter from ganglion cells of the sympathetic system. Com- 

 parative anatomy likewise indicates this separate origin of the 

 two parts of the gland ; in sharks and other members of the 

 Elasmobranche the cortical part forms the inter-renal body, an 

 unpaired organ, separated from the medullary portions which are 

 situated above the kidneys and form the suprarenal bodies. 

 Physiological experiments show that extracts of the former organ 

 produce no characteristic effects, but the latter organ contains 

 an active substance similar to that found in the medulla of the 

 mammalian suprarenal gland. 



The microscopic structure of the mammalian suprarenal body 

 shows that the gland, especially the medullary portion, is extremely 

 vascular, and the suprarenal vein is surrounded in the medulla 

 by a large bundle of involuntary muscle fibres, the function of 

 which may be to regulate the circulation through the organ. In 

 addition nerve-cells and branched cells containing granules of pig- 

 ment are characteristic of the medulla. 



The physiological evidence relating to the function of the 

 glands can be divided into the effects of partial or complete re- 

 moval of the capsules and the effects produced by injections of 

 adrenal extracts. Brown-Sequard found that the removal of the 

 suprarenal glands caused death in guinea-pigs, rabbits, dogs, cats, 

 rats, mice, and pigeons ; the mean duration of life after the opera- 

 tion was in rabbits nine hours, in dogs and cats fourteen hours ; 

 the symptoms which were generally observed were loss of appetite 

 and of muscular power, cardiac weakness and convulsions. 



Experiments by other observers have confirmed and extended 

 Brown-Sequard' s work. Removal of one gland does not cause 

 death, and the remaining gland undergoes hypertrophy, and thus 

 the animal appears to compensate for the loss of the one gland. 

 Death generally occurs within one or two days after the removal 

 of the second gland. The symptoms described by most observers 

 are almost identical with those of Addison's disease, muscular 

 weakness, loss of appetite, loss of tone in the vascular system, 

 and paralysis of the respiratory muscles. Pigmentation has been 

 observed in animals which have lived for a longer time after the 

 excision of the glands. 



The blood of animals, which have died after removal of the 

 suprarenal capsules, is said to possess toxic properties, and to 

 produce, when it is injected into healthy animals, symptoms 



