418 PHYSIOLOGY. 



proteid. The total percentage in the thymus gland is about 12.29 

 per cent. When it is desired to produce experimental intravascular 

 clotting,, the thymus is usually employed as the source for the nucleo- 

 proteid. This property is not characteristic of the thymus, for it is 

 found in all protoplasm. 



Function. Extirpation gives few positive results, but chemical 

 investigation shows that the parenchyma of the gland contains a large 

 number of products that indicate that it possesses very considerable 

 metabolic activity. As long as the thymus gland exists, it seems to 

 take part in the production of white corpuscles like other varieties of 

 lymphatic tissue. Some authors claim for it the production of red 

 corpuscles in early life. 



Extracts of the thymus, when injected subcutaneously, have been 

 shown by Ott to increase the pulse-rate, with a momentary rise 

 of pressure, followed by a fall. This has been confirmed by Svehla 

 and Swale Vincent. Svehla found that extirpation of the thymus 

 of the frog kills it. Swale Vincent, however, did not find that re- 

 moval of the gland of the frog was necessarily fatal, as his frogs lived 

 thirty-six days after the operation. According to Vincent, extirpa- 

 tion of the gland of guinea-pigs did not affect the animal in any way. 



PITUITARY BODY. 



The pituitary body (hypophysis cerebri) is a small, reddish-gray, 

 vascular mass,, weighing from five to ten grains. It is oval in shape, 

 situated in the pituitary fossa of the sphenoid bone, and is connected 

 with the end of the infundibulum. The body is retained in position 

 by a process of dura mater derived from the inner wall of the cav- 

 ernous sinus. 



The thyroid, adrenals and pituitary produce substances which are 

 important and have an antagonistic action on blood-pressure. Hence 

 they have been called regulators of nutrition and circulation. 



Structure. The pituitary body has two parts, a large anterior 

 lobe of glandular structure, and a smaller posterior lobe. The anterior 

 lobe, the hypophysis cerebri, arises from the epithelium of the mouth. 

 The posterior lobe, nervous lobe, or infundibular body, is an outgrowth 

 of the infundibulum of the brain, and in the adult is connected to it 

 by a long stalk. Howell has shown that extracts of the anterior lobe 

 of the hypophysis have no special action on the circulation. The pos- 

 terior infundibular lobe has an internal secretion which increases the 

 secretion of urine and dilates the blood-vessels of the kidneys. 



In the pituitary there is a passage of colloid from the cells of 



