THE THYROID APPARATUS 89 



where the gas metabolism approaches the normal, thyroid treat- 

 ment increases the amount up to 15 per cent. The use of thyroid 

 preparations produces a complete change in the conditions 

 governing the metabolism of albumin. As a consequence of the 

 improvement in appetite, the amount of albumin ingested is much 

 larger, and the excretion of nitrogen becomes very much in- 

 creased; consequently, there is an appreciable loss of nitrogen 

 which is counteracted only by raising the entire caloric supply. 

 The larger part of the N-excretion is derived from pathological 

 deposits, which, at the same time, disappear. The increased 

 supply of albumin may, at a later stage, occasion a deposit of 

 albumin as tissue. 



Scholx concludes that the metabolic conditions of cretinism are 

 singularly like those of myxcedema. But the effect of thyroid 

 extract upon the metabolism of nitrogen is not the same in 

 cretinism as in myxcedema. In the former condition it closely 

 resembles that seen in Graves's disease. Nevertheless, Scholz 

 does not conclude from this that myxcedema and endemic cretinism 

 are opposed conditions ; he is of the opinion that, as far as 

 metabolism is concerned, cretinism is a similar condition to 

 myxoedema, but is more advanced. 



THE PHYSIOLOGICAL EFFECTS OF THYROID 

 SUBSTANCES. 



Of the physiological effects of thyroid extract, the first to be 

 considered is the effect which it produces upon the circulatory 

 system. Oliver and Schafer (1894) pointed out that the injection 

 of watery or glycerine thyroid extracts into the veins was followed 

 by a reduction in blood-pressure, the cardiac activity remaining 

 unchanged. This is confirmed by the observations of many 

 others (Haskovec, Georgiewsky, Guinard and Martin, Feny- 

 vessy, Ocana, Patta, v. Fiirth and Schwarz, Farini and Vidoni). 

 Certain authors (Heinatz, Livon, Patta) noticed that an increase 

 in blood-pressure was brought about by thyroid extract. Farini 

 and Vidoni found that, during artificial circulation through the 

 hinder extremities of cats and rabbits, the effect was vaso-contractor, 

 never vaso-dilator. Though Schafer declares that the cardiac 

 rhythm is unaffected by thyroid extract, yet Haskovec, Guinard 

 and Martin, and Svehla all found that the decrease in blood- 

 pressure was accompanied by a marked acceleration of the heart's 

 action. Others, again, report a definite slowing of the pulse. 



The effects of iodothyrin and of iodothyroglobulin upon the 

 circulatory apparatus were tried by v. Cyon and Oswald. They 

 found that, when injected into the veins of dogs and rabbits, these 

 substances produced a fall in blood-pressure, together with a 

 stronger and slower heart action, and that these phenomena 

 persisted after resection of the vagi and after administration of 



