598 CHEMICAL PATHOLOGY OF THE DUCTLESS GLANDS 



How the thyroid or its secretion modifies metabolism is not yet understood. 

 One is reminded of the effects of kinases upon enzymes and their antecedents, 

 and it may he imagined that the th\roid secretion activates both proteolytic and 

 oxidative "enzymes within the cells. Shryver,' indeed, did find that administra- 

 tion of thyroid to dogs for some time lief ore killing them causes their li\-er tissue 

 to undergo autolysis more rapidly than normal, although Wells* had been unable 

 to observe any increased amount of autolysis when thyroid extracts acted upon 

 liver tissue in vitro. Experimental observations show that carbohydrate meta- 

 bolism is much influenced by the thyroid, so that thyroidectomized animals may 

 fail to show glycosuria from various procedures that usually produce it (King),^ 

 and they are incapable of utilising sugar injected parenterally as well as normal 

 animals;^" they also exhibit an excessive creatine output. Protracted feeding of 

 thyroid to growing animals reduces the weight attained and causes marked en- 

 largement of suprarenals, heart, liver, spleen, testes, ovaries and pancreas; the 

 pituitary and uterus are reduced in size." 



Detoxicatory Function. — The evidence that the thyroid has for 

 its function the destruction or neutralization of poisonous substances 

 formed in metaboHsm or through intestinal putrefaction is as follows: 



(1) After total removal of the thyroid from many species of animals acute 

 symptoms develop that suggest strongly an intoxication. 



(2) After removal of the thyroid, marked changes occur in the blood, there 

 being a severe anemia (as low as 2,000,000 red corpuscles), with some leucocytosis, 

 and there occur structural changes in the blood-vessel walls (Ivishi).'^ Cyto- 

 plasmic degeneration of the liver, kidneys, and myocardium may also result (Ben- 

 sen). ^^ These effects suggest strongly ^he presence of poisonous substances in the 

 blood of persons or animals lacking sufficient thyroid tissue. 



(3) All the effects of thyroidectomy are more marked in carnivorous animals 

 than in herbivora; indeed, the latter may be able to live in fair condition for several 

 years without a thyroid." Administration of meat to thyroidectomized herbi- 

 vora or omnivora causes a great increase in the symptoms, while thyroidectomized 

 carnivora do much better if kept without meat. Thus, Blum'^ found that thy- 

 roidectomized dogs, which \\ere doing well on a milk diet, developed symptoms 

 of athyreosis immediately they were given meat. This fact has been interpreted 

 as indicating that toxic materials are formed from meat in the intestinal tract, 

 which under normal conditions are neutralized by the thyroid. On the other 

 hand, one may well imagine that the so-called autointoxication in athyreosis is 

 not from intestinal putrefaction, but is due to the products of incomplete meta- 

 bolism of proteins within the tissues, which are destroyed when protein metabolism 

 is normal, but not when the metabolism-favoring influence of the thyroid is want- 

 ing. It should also be added that the presence of specific poisonous substances in 

 the blood or urine of thyroidectomized animals has not been conclusivelj' estab- 

 lished.'" 



7 Jour, of Physiol, 1905 (32), 159. 



* Amer. Jour. Physiol., 1904 (11), 351; corroborated bv Morse, Jour. Biol. 

 Chem., 1915 (22), 125. 



» Jour. Exper. Med., 1909 (11), 6G5. 



10 Underbill and Saiki, Jour. Biol. Chem., 1908 (5), 225. 



"Herring, Quart. Jour. Exp. Physiol., 1917 (11), 231; Kojima, ibid., p. 255. 



12 Virchow's Arch., 1904 (176), 260. 



" Virchow's Arch., 1902 (170), 229. 



^* Part of these results may be due to the fact that in some herbivora tlie 

 parathyroids are so far separated from the thyroid that they are not ordinarily 

 removed in thyroidectomy, whereas in many carnivora complete removal of 

 parathyroids with the thvroids is more likely to be accomplished. 



1" Virchow's Arch., 1900 (162;, 375. 



I'Remedi (Lo Sperimentale, 1902; abst. in Cent. f. Path., 1903 (14), 695) 

 claims that tetanus toxin and other bacterial poLsons, when injected into the 

 thyroid gland, are harmless, whicli he attributes to n ncutraliziition by tlie 

 colloid. This observation is discredited by the work of Basinger, Jour. Infect. 

 Dis., 1917 (20), 131. 



