METABOLISM, NUTRITION AND DIETETICS 489 



names it epinephrin. It is a base of alkaloidal nature, 

 whose percentage composition corresponds to the formula 

 C 17 H 15 NO 4 . The function of the capsules is to secrete this 

 substance, which is probably of great physiological im- 

 portance for maintaining the tonicity of the muscular tissues 

 in general, and especially of the heart and arteries. It is 

 possible that in addition toxic bodies are neutralized or 

 destroyed in the glands. The existence of secretory fibres 

 for the suprarenal capsules in the splanchnic nerves has 

 been rendered probable by the experiments of Dreyer, who 

 finds that the amount of active substance in the blood of 

 the suprarenal vein, as tested by its physiological effect 

 when injected into an animal, is increased by stimulation of 

 those nerves. 



Pituitary Body. When the pituitary body is removed (in 

 cats or dogs), death generally occurs within a fortnight, with 

 symptoms some of which for instance, muscular tremors 

 and spasms resemble those that follow excision of the 

 thyroid. It has been stated, too, that the pituitary undergoes 

 (compensatory ?) hypertrophy after thyroidectomy, and some 

 observers have accordingly assumed a similarity of function 

 for these organs. But, according to Schafer, there is no 

 basis for this assumption. For in man pathological changes 

 in the pituitary body are associated, not with myxoedema, as 

 disease of the thyroid is, but with another condition, called 

 acromegaly, in which the bones of the limbs and face 

 become hypertrophied. The effects on the vascular system 

 of intravenous injection of extracts of the gland are also 

 very different from those caused by thyroid extract. Extracts 

 of the anterior lobe, or hypophysis, are inactive. The pos- 

 terior lobe, or infundibular body, contains two active sub- 

 stances, one pressor and the other depressor. The former is 

 soluble in salt solution, but insoluble in absolute alcohol and 

 ether ; while the latter is soluble in salt solution as well as 

 in alcohol and ether. The pressor substance causes a great 

 rise of blood-pressure, due partly to constriction of the 

 arterioles and partly to an increase in the force of the heart- 

 beat, both of which are brought about by direct action. This 

 rise of pressure lasts for a considerable time, and is some- 



