334 



THE DUCTLESS GLANDS. 



[CH. XXIII. 



(2.) The medullary substance consists of a coarse rounded or 

 irregular meshwork of fibrous tissue, in the alveoli of which are 

 masses of multinucleated protoplasm (fig. 307) ; numerous blood- 

 vessels ; and an abundance of nerve-fibres and cells. The cells 

 are very irregular in shape and size, poor in fat, and often 

 branched ; the nerves run through the cortical substance, and 

 anastomose over the medullary portion. 



The cells of the medulla are characterised by the presence of 

 certain reducing substances. One of these takes a brown stain 

 with chromic acid, and gives other colour reactions ; it is, there- 

 fore, called a chromogen. Another is similar in many of its 



f tStt* 







Fig. 307. Section through a portion of the medullary part of 'the supra-renal of guinea- 

 pig. The vessels are very numerous, and the fibrous stroma more distinct than in 

 the cortex, and is, moreover, reticulated. The cells are irregular and larger, clear, and 

 free from oil globules. (8. K. Alcock.) 



characters to jecorin, a lecithin-like substance also found in the 

 liver, spleen, and other organs. 



Function. The immense importance of the supra-renal bodies 

 was first indicated by Addison, who, in 1855, pointed out that 

 the disease now known by his name is associated with pathological 

 alterations of these glands. This was tested experimentally by 

 Brown-Sequard, who found a few years later that removal of the 

 supra-renals in animals is invariably and rapidly fatal. The 

 symptoms are practically the same (although more acute) as 

 those of Addison's disease, namely, great muscular weakness, loss 

 of vascular tone, and nervous prostration. The pigmentation 

 (bronzing) of the skin, however, which is a marked symptom in 

 Addison's disease, is not seen in animals. The experiments of 



