CH. XXV.] THE PITUITARY BODY 343 



There are some points of interest in the development and com- 

 parative physiology of the suprarenals. In mammals the medullary 

 portion is developed in connection with the sympathetic, and is at 

 first distinct and outside the cortical portion which is developed in 

 connection with the upper part of the Wolffian body ; it gradually 

 insinuates itself within the cortex (Mitsukiri). In Elasmobranch 

 fishes the suprarenals consist throughout life of separate portions ; 

 one, the inter-renal body, is median in position and single ; this corre- 

 sponds to the cortex of the mammalian suprarenal ; extracts of this 

 are inactive, and in the Teleostean fishes, where it is the sole repre- 

 sentative of the suprarenal, it may be removed without any harm to 

 the animal. The other portion of the Elasmobranch suprarenal is 

 paired, and derived from the sympathetic ganglia. This corresponds 

 to the medulla ; it contains the same chromogen as the medulla of 

 the mammalian suprarenal, and extracts of it have the same physio- 

 logical action (S. Vincent). 



The tissue of the suprarenal medulla is often called chrcmophil tissue, on 

 account of the ready way in which it stains with chromic salts. Such tissue is, 

 moreover, not confined to the suprarenal, but is found in scattered patches in the 

 retro-peritoneal region and in many sympathetic ganglia, especially in the 

 abdomen. The histological resemblance is accentuated by the presence of 

 numerous sympathetic cells in the suprarenal medulla. The chromophil tissue 

 wherever found always yields adrenaline. 



The Pituitary Body. 



This occupies the sella turcica of the sphenoid bone. It may be 

 divided into three parts, which show developmental, structural and 

 functional differences. 



(1) The anterior lobe is developed as a tubular prolongation from 

 the epiblast of the buccal cavity, but the growth of intervening 

 tissue soon cuts off all connection with the mouth. It consists of 

 large granular cells and numerous blood-vessels. Its precise function 

 is undetermined, although probably it is a vascular gland pouring 

 an internal secretion into the blood, which influences growth. 

 Abnormal hypertrophy of the pituitary produces the condition 

 known as acromegaly, in which the bones of the face and limbs 

 hypertrophy ; and if the view advanced above of the anterior lobe 

 is correct, the condition is caused by an increase of the internal 

 secretion. Feeding young animals and children in the anterior 

 lobe hastens the growth of their skeletal tissues. 5.-,; |-H.~ " 



(2) The pars intermedia. This lies between the anterior and 

 posterior lobes, and forms a closely fitting investment of the latter 

 lobe. It is developed in association with the anterior lobe, and 

 consists of finely granular cells arranged in layers closely applied to 

 the body and neck of the posterior lobe and the under surface of 

 adjacent parts of the brain. Colloid material occurs between the 



