SUPRARENAL CAPSULES. 479 



mals after extirpation of the spleen ; but these results are hy no means invariable. We 

 have often removed the spleen from dogs and kept the animals for months without 

 observing any thing unusual ; and, on the other hand, we have observed the change in 

 disposition and the development of an unnatural appetite, in animals after removal of 

 one kidney. These effects were also very well marked in an animal with biliary fistula, 

 that lived for thirty-eight days. In the latter instance, the voracity could be explained 

 by the disturbance in digestion and assimilation produced by shutting off the bile from 

 the intestine ; but these phenomena occurring after removal of one kidney, which ap- 

 peared to have no effect upon the ordinary functions, are not so readily understood. We 

 have observed both increase in the appetite and the development of extraordinary ferocity 

 after extirpation of one kidney almost invariably, since our attention has been directed 

 to this point ; and, in the experiments of which records were preserved, these effects 

 were very marked. In one, a dog lived for nearly two years with one kidney and was 

 finally killed. The appetite was voracious and depraved. He would eat dogs' flesh 

 greedily. In another, death took place in convulsions, forty-three days after removal of 

 one kidney, the animal having apparently recovered from the operation. This dog was 

 very ferocious, had an extraordinary appetite, and would eat faeces, putrid dogs' flesh, etc., 

 which the other dogs in the laboratory would not touch. The other dog entirely recov- 

 ered from the operation of removing one kidney and presented the same phenomena. 



In view of the above facts, it must be admitted that removal of the spleen in the 

 lower animals and the human subject has thus far demonstrated nothing, except that this 

 part is not essential to the proper performance of the vital functions. The voracity 

 which occasionally follows the operation in animals is one of the phenomena, like the 

 increase in the size of animals after castration, for which physiologists can offer no satis- 

 factory explanation. 



It is evident from the foregoing considerations that, notwithstanding the great amount 

 of literature upon the anatomy and functions of the spleen, physiologists have no definite 

 knowledge of any important office performed by this organ. With this conclusion, we 

 pass to a consideration of the other ductless glands, the physiology of which is, unfortu- 

 nately, even more unsatisfactory. 



Suprarenal Capsules. 



The theories that have been advanced with regard to the function of the suprarenal 

 capsules have not, as a rule, been based upon anatomical investigations, but have taken 

 their origin from pathological observations and experiments upon living animals. This fact 

 detracts from the physiological interest attached to the structure of these bodies, and we 

 shall consequently treat of their anatomy very briefly. 



The suprarenal capsules, as their name implies, are situated above the kidneys. They 

 are small, triangular, flattened bodies, situated behind the peritoneum, and capping the 

 kidneys at the anterior portion of their superior ends. The left capsule is a little larger 

 than the right, and is rather semilunar in form, the right being more nearly triangular. 

 Their size and weight are very variable in different individuals. Of the different esti- 

 mates given by anatomists, we may state, as an average, that each capsule weighs about 

 one hundred grains. They are about an inch and a half in length, a little less in width, 

 and a little less than one-fourth of an inch in thickness. 



The weight of the capsules, in proportion to that of the kidneys, presents great vari- 

 ations at different periods of life ; and they are so much larger in the foetus than after 

 birth, that some physiologists, in the absence of any reasonable theory of their function in 

 the adult, have assumed that their office is chiefly important in intra-uterine life. Meckel 

 states that they are easily distinguished in the foetus of two months ; at the end of the 

 third month, they are a little larger and heavier than the kidneys ; they are equal in size 

 to the kidneys (though a little lighter) at four months ; and, at the beginning of the sixth 

 month, they are to the kidneys as two to five. In the foetus at term, the proportion is as 



