THE DUCTLESS GLANDS. [CH. xxm. 



medium in position and single ; this corresponds to the cortex 

 of the mammalian supra-renal ; extracts of this are inactive, and 

 in the Teleostean fishes, where it is the sole representative of the 

 supra-renal, it may be removed without any harm to the animal. 

 The other portion of the Elasmobranch supra-renal is paired, 

 and derived from the sympathetic ganglia. This corresponds to 

 the medulla ; it contains the same chromogen as the medulla 

 of the mammalian supra-renal, and extracts of it have the same 

 physiological action (S. Vincent). 



The Pituitary Body. 



This body is a small reddish-grey mass, occupying the sella 

 turcica of the sphenoid bone. It consists of two lobes a small 

 posterior one, consisting of nervous tissue ; and an anterior larger 

 one, resembling the thyroid in structure. A canal lined with 

 flattened or with ciliated epithelium passes through the anterior 

 lobe ; it is connected with the infundibulum. The alveoli are 

 approximately spherical ; they are filled with nucleated cells of 

 various sizes and shapes not unlike ganglion cells, collected 

 together into rounded masses, filling the vesicles, and contained 

 in a semi-fluid granular substance. The vesicles are enclosed by 

 connective-tissue, rich in capillaries. Disease of the pituitary 

 body produces the condition called acromegaly, in which the 

 bones of limbs and face hypertrophy. 



When the gland is removed in animals, tremors and spasms 

 occur like those which take place after removal of the thyroid. 

 Death usually occurs within fourteen days. Some observers have 

 stated that overgrowth of the pituitary occurs after excision 

 of the thyroid. But there is no ground for the assumption that 

 the two glands have a similar function. Acromegaly is a very 

 different disease from myxoedema. The injection of extracts 

 of the organs are also different. Thyroid extract produces a fall 

 of arterial pressure. Extracts of the anterior lobe (hypophysis) 

 of the pituitary body are inactive ; but extracts of the posterior 

 lobe or infundibular body contain two active substances, one of 

 which produces a rise, and the other a fall of blood-pressure. 

 A second dose of the former of these injected soon after the first 

 dose is inactive ; and so it is not the same thing as in supra-renal 

 extract. The chemical nature of the two substances is not 

 known. 



The Pineal Gland. 



This gland, which is a small reddish body, is placed beneath 

 the back part of the corpus callosum, and rests upon the corpora 



