246 Herring 



t^ 



the animals were killed, and their organs compared with those of rats which 

 had led a more quiescent existence. The long-continued exei-cise produced 

 hypertrophy of the heart, kidneys, and liver to about 20 per cent, above the 

 normal. The testes were increased in weight by 12 per cent., the ovaries 

 by 84 per cent. The spleen was decreased in weight. Of the ductless 

 glands the thyroid showed a diminution in size, the suprarenals were 

 unaltered in the male, but hypertrophied by nearly 48 per cent, in the 

 female. Changes in the thymus were uncertain. The pituitary body 

 was increased in the male by 10 per cent., and decreased in the female 

 by 22 per cent. 



My results are similar in most respects to those of Ho skins, but differ 

 from his, and from Hatai's, in the much greater degree of hypertrophy 

 reached by certain organs, e.g., the suprarenals, heart, and kidneys, to 

 which must be added the pancreas, an organ not specially investigated by 

 either Hoskins or Hatai. In respect to the other organs — the liver, 

 spleen, testes, and ovaries — our results agree, and it is probable that the 

 comparatively small degree of hypertrophy observed in these organs is 

 due, as Hoskins surmises, to the generally increased rate of metabolism of 

 the body induced by thyroid. It does not seem to me likely that the 

 excessive hypertrophy of the heart and kidneys, which in extreme cases 

 are more than trebled in weight, can be solely a.scribed to a general action 

 of thyroid upon metabolism. Such a result may be possible, but as far as 

 I am aware it did not occur in any of Hatai's rats which were subjected 

 to exercise for a considerable portion of their normal life's span. The 

 excess of thyroid in the body of the thyroid-fed animal must upset the 

 normal equilibrium which in all probability exists between the internal 

 secretions of the ductless glands. Hyperthyroidism stimulates the pro- 

 duction of adrenalin. It also produces a striking hypertrophy of the 

 pancreas, but whether this is associated with an increase of the islets of 

 Langerhans is not decided. The growth of the pituitary body is checked 

 in females at any rate, and possibly in males, though the evidence for this 

 is doubtful. This disturbance of the relations between the ductless glands 

 cannot be ignored, though its significance is not yet capable of being 

 thoroughly explained. 



It is probable that in hyperthyroidism many factors are brought into 

 play. In this connection the work of Eppinger, Falta, and Rudinger (5) 

 must be cited. These observers claim to have established certain relation- 

 ships between the ductless glands. Removal of one gland produces direct 

 results on the body from the loss of its secretion, and indirect results from 

 the disturbances set up among the others. Between thyroid and pancreas, 

 and between pancreas and chromaffin tissue there is a mutual restraining 

 influence ; between thyroid and chromaffin tissue there exists a mutually 

 stimulating influence. While not committing myself to an agreement with 

 the details enunciated by Eppinger, Falta, and Rudinger, I believe there 

 is evidence to support some of their views. 



