INTERRELATIONS 399 



that thyroidectomy depresses the function of the chromaphil 

 tissues. 



The Viennese school has elaborated a very complicated 

 theory. The thyroid and parathyroids are antagonistic to 

 each other. While the former stimulates the sympathetic, 

 the latter inhibits this system. The parathyroid is the ally of 

 the pancreas in checking or inhibiting metabolism, while the 

 adrenals and the thyroid increase it. So that when the thyroid 

 is put hors de combat four things happen : (1) Loss of thyroid 

 secretion, inducing slowed or diminished metabolism ; (2) 

 Absence of stimulation of the adrenals (that is to say, the 

 chromaphil tissues) ; (3) Relaxation of the inhibition of the 

 pancreas ; (4) Diminished excitability of the nerves to the 

 thyroid, that is, branches of the vagus. 1 



In regard to superthyroidism, there is some evidence that 

 the amount of adrenin in the blood is increased in this con- 

 dition. This evidence, though not very positive or great in 

 amount, supports the theory that the secretion of the thyroid 

 acts as a direct stimulant to the chromaphil tissues, causing 

 them to yield adrenin to the blood in larger quantities. 



There are grounds for extreme scepticism regarding all this 

 work. 



Cramer has put forward the view that the thyroid and the 

 adrenal are part of an apparatus which controls the tempera- 

 ture of the body. He regards the adrenal as a gland in itself 

 and not as consisting of two independent constituents. One 

 of its functions is to act with the thyroid as a humoral 

 mechanism regulating body temperature, and supplementing 

 the action of the nervous system. The thyroid hormone 

 mobilizes liver glycogen by increasing the production of 

 adrenin and sensitizing the sympathetic nerve-endings. At 

 the same time adrenin constricts the arterioles of the skin, 

 thereby diminishing the loss of heat from the body. Cramer 

 has adduced a number of experimental and pathological 

 observations in support of this theory. 



Relations between the Thyroid and Pituitary Bodies 

 Clinical evidence as to pituitary hypertrophy as a result of 

 thyroid deficiency is unsatisfactory, but the experimental 



1 It'is more usually admitted that the specific nerves to the thyroid are 

 derived from the sympathetic (see p. 308). 



