34 SECRETION 



These bodies must produce an internal secretion which is re- 

 moved by way of the adrenal veins. It may destroy toxic sub- 

 stances in the blood. A solution injected into the circulation 

 certainly affects the middle wall of the vessels, causing contrac- 

 tion, and a heightened pressure. The heart is also notably 

 inhibited. It is not thought that the effect on the vessels is 

 brought about through the vaso-motor nerves, but by direct 

 excitation of the muscular substance. Little in fact is known 

 about the secretion, except that it is necessary to life. Abel has 

 isolated an alkaloid, epinephrine, which is claimed to be the 

 active principle. These glands are the seat of lesions in Addison's 

 disease, and many cases of this malady are at least favorably 

 influenced by the use of adrenal extract. 



Pituitary Body. 



The pituitary body lying in the sella turcica on the superior 

 surface of the sphenoid bone, also produces an internal secretion 

 of physiological value. Its removal is regarded as causing death. 

 Howell has shown that injection of extract from the posterior 

 division occasions a rise of temperature and slowing of the heart. 

 Its situation makes satisfactory experiments very difficult. 



Testis and Ovary. 



The testes and ovaries, though not probably true glands, 

 also may produce an internal secretion of obscure physiological 

 value. It is not essential to life. Injections of extracts from 

 these bodies are claimed to have a remarkable stimulating effect 

 upon the nervous and muscular systems. In mental and physical 

 disturbances occasionally following removal of the ovaries, gyne- 

 cologists often find administration of the ovarian extract to be 

 beneficial. 



