ARTICLES 247 



a high sugar tolerance. The condition was essentially chronic, 

 and death usually supervened as the result of intercurrent in- 

 fection. Exceptions to the above may be found in the records 

 of most observers, e.g. cats and dogs have occasionally showed 

 no discomfort after thyroidectomy, or merely transient symp- 

 toms. Nevertheless, despite the discrepancies which have 

 been recorded, there is no doubt that the general effects of 

 thyroid deprivation, whether produced by disease or excision, 

 are strikingly similar, and may be observed in all mammals 

 with few exceptions. These exceptions may be explained as 

 the result of anatomical peculiarities such as the presence of 

 remote accessory thyroids (Gley) or the vicarious functioning 

 of other glands, e.g. parathyroids (Vincent and Jolly) or the 

 pituitary [Rogowitsch (1886) found this gland to be hyper- 

 trophied after thyroidectomy]. 



The Effects of Increased Secretion : Hyperthyroidism. — Here, 

 as in hypothyroidism, the effects may be produced either ex- 

 perimentally or as the result of disease. Hyperthyroidism may 

 be artificially induced by injecting a liquid extract of the 

 gland substance or by feeding with the gland itself. The 

 former method was first employed by Oliver and Schafer (1895). 

 They showed that the only immediate result of injecting was 

 a temporary lowering .of blood-pressure due to dilatation of 

 the blood-vessels. Whether this is a specific effect is doubt- 

 ful, since a similar result may be obtained with most tissue 

 extracts. On prolonged administration, a characteristic train 

 of symptoms develops. The skin becomes lax, hot and moist 

 from increased perspiration. Weight is lost, and fat disappears 

 from regions where it is normally abundantly present, e.g. sub- 

 cutaneous tissues, bone-marrow, etc. [Leichtenstern (1893)]. 

 Metabolism is accelerated, and there is an increased consump- 

 tion of food [Ord, White, Mendel (1893)], of oxygen [Magnus- 

 Levy (1895)], and hence a greater excretion of nitrogen and 

 carbon dioxide. The liver is emptied of its glycogen [Krause 

 and Crammer (19 13)], and the pancreas (rat) exhibits extensive 

 mitoses within a week of feeding [Kojima (191 7)]. Sugar 

 tolerance is lowered and glycosuria readily provoked. The 

 heart hypertrophies [Herring (1916)] and beats at a faster 

 rate (tachycardia), and the blood-pressure is persistently 

 raised. Nervous activity is also enhanced, tremors, mental 

 excitement, protrusion of the eyeballs (or exophthalmos), and 

 dilatation of the pupils being commonly observed. Some of 

 the above symptoms, e.g. those pertaining to the heart, blood- 

 pressure, and eye, are the same as those produced by stimula- 

 tion of the sympathetic, and are probably effected by the 

 internal secretion of the suprarenal gland (adrenalin). Evidence 

 of an increased secretion of adrenalin is supplied by Fraenkel 



