SUPRARENAL CAPSULES. 419 



corpuscles, the coloring matter being changed into other pigmentary matters, 

 and that it also produces new red corpuscles. After removal of the spleen, 

 the red blood-corpuscles are diminished in number, and the proportion of 

 leucocytes is increased. This condition continues for about six months, but 

 after that time, in dogs, the marrow of the long bones, which normally is 

 yellow, becomes red, assuming the character of the marrow concerned in the 

 formation of red corpuscles. Temporary diminution of red corpuscles and 

 increase of leucocytes have been observed in the blood in cases of extirpation 

 of the spleen in the human subject. 



Whatever uses the spleen has in connection with the development of red 

 and of white blood-corpuscles it shares with the red marrow of the bones 

 and the so-called lymphatic glands. 



The above expresses about all that is known with regard to the physiology 

 of the spleen. 



SUPRARENAL CAPSULES. 



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 semi- 

 lunar in form, the right being more nearly triangular. Their size and 

 weight are very variable in different individuals. It may be stated, as an 

 average, that each capsule weighs about one hundred grains (6*5 grammes). 

 The capsules are about an inch and a half (38 mm.) in length, a little less in 

 width, and a little less than one-fourth of an inch (6-4 mm.) in thickness. 



The weight of the capsules, in proportion to the weight of the kidneys, 

 presents great variations at different periods of life. They are relatively much 

 larger in the foetus than after birth. 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 (Meckel). In the foetus at term the 

 proportion is as one to three, and in the adult, as one to twenty-three. 



The color of the capsules is whitish-yellow. They are completely cov- 

 ered by a thin, fibrous coat, which penetrates their interior, in the form of 

 trabeculae. Upon section they present a cortical and a medullary substance. 

 The cortex is yellowish and ^ to -^ of an inch (1 to 2 mm.) in thickness. It 

 surrounds the capsule completely and constitutes about two-thirds of its sub- 

 stance. The medullary substance is whitish, very vascular, and is remark- 

 ably prone to decomposition, so that it is desirable to study the anatomy of 

 these bodies in specimens that are perfectly fresh. 



Cortical Substance. The cortical substance is divided into two layers. 

 The external layer is pale-yellow and is composed of closed vesicles, rounded 

 or ovoid in form, containing an albuminoid fluid, cells, nuclei and fatty glob- 

 ules. This layer is very thin. The greater part of the cortical substance is of 

 a reddish-brown color and is composed either of closed tubes containing 



