3/6 USES OF THE LIVER DUCTLESS GLANDS 



the supposition that the ductless glands effect certain changes in 

 the blood is now regarded by physiologists as the most reasonable of the 

 many theories that have been entertained concerning their uses in the 

 economy. Under this idea, these organs have been called blood-glands 

 or vascular glands, and their action is now known as internal secretion. 

 Under the head of ductless glands, are classed the suprarenal capsules, 

 the spleen, the thyroid gland, the thymus, and sometimes the pituitary 

 body and the pineal gland. 



SUPRARENAL CAPSULES 



The suprarenal capsules, or adrenals, 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 variable in different individuals. 

 It may be stated as an average that each capsule weighs about one 

 hundred grains (6.5 grams). The capsules are about an inch and a half 

 (38 millimeters) in length, a little less in width, and about one-fourth 

 of an inch (6.4 millimeters) 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. In the foetus at term the proportion is as one 

 to three, and in the adult, as one to twenty-three (see Plate XVI, Fig. 3). 



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

 covered by a thin fibrous coat which penetrates their interior in the 

 form of trabeculae. On section they present a cortical and a medul- 

 lary substance. The cortex is yellowish and ^ to T ^ of an inch ( i to 

 2 millimeters) in thickness. It surrounds the capsule completely and 

 constitutes about two-thirds of its substance. The medullary substance 

 is whitish, very vascular, and is remarkably 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 albuminous liquid, cells, nuclei 

 and fatty globules. This layer is very thin. The greater part of the 





