606 LECTURE XXVI. 



lar tremors first appear, which gradually pass into clonic spasms, finally 

 resulting in tetanus. The muscular tremors are not of peripheral origin, 

 for they disappear on section of the peripheral nerves. Apparently the 

 thyroid gland in some way influences the higher nerve centers. It is 

 evident, however, that the lower nerve centers are also affected, for the 

 tremors continue after the removal of the cortical brain area concerned 

 with the movement of the part. In the case of herbivora, the ruminants, 

 rodents, and monkeys, tetany does not as a rule take place. Instead, 

 cachexia becomes a prominent symptom. This contrast of symptoms in 

 the two classes of animals, which was made more puzzling by reason of 

 the fact that with the herbivora sometimes tetany appears and sometimes 

 does not, has recently been offered an explanation. We have already 

 mentioned the presence of the parathyroid glands. In the carnivora 

 these are included in the main gland, whereas in the herbivora they are 

 separated from it. For this reason the parathyroid glands are always 

 removed from carnivora in cases of complete ablation of the thyroid 

 gland, whereas in the herbivora this is rarely the case. In fact, it has 

 usually been found that tetany in herbivora results when these parathy- 

 roid glands are removed. 1 According to this discovery, it would seem 

 that the parathyroid glands and the main gland have different functions. 

 It seems highly desirable that clinical observations should receive renewed 

 study with regard to this point. 



It might be objected with regard to the experiments in the ablation of 

 the thyroid gland that the operation itself may be such a severe one that 

 other injuries can produce some, at least, of the observed symptom com- 

 plex. This objection, however, has been successfully refuted by means 

 of a great many experiments. In the first place, the entire operation 

 may be performed, except that the gland is allowed to remain in place,, 

 without any of the symptoms occurring. Again, if a part of the organ 

 is allowed to remain in the body, the symptoms do not appear; and, 

 finally, if a part of the organ is transplanted to another part of the body, 

 the whole operation may then be carried out without fatal results. Such 

 experiments were performed by Schiff and have been repeated by Eisels- 

 berg 2 in a particularly convincing manner. The latter extirpated half of 

 the thyroid gland from a cat and grafted it in the wound between the 

 abdominal fascia and the peritoneum. Then, after this had been accom- 

 plished, the other half of the organ was carefully removed. The animal 

 was kept under observation for two months without its showing any 



1 Cf. E. Gley: Compt. rend. soc. biol. Paris (9), 841 (1891). Vassale et Generali: 

 Arch. ital. biol. 25, 459 (1896); 26, 61 (1896). Biedl: Innere Sekretion, Berlin, 1904. 

 MacCallum: Zentr. allg. Path. u. path. Anat. 16, No. 10 (1905). 



2 A. Freiherr von Eiselsberg, Wiener klin. Wochschr. 5, 81 (1892). 



