956 THE INTERNAL SECRETIONS 



(Cyon), this view being based upon the fact that it is placed directly 

 in the path of the cerebral vessels and contains at times anastound- 

 ingly large amount of blood. ^ The latter peculiarity, in particular, 

 led Tiedemann to assume that it is a blood-forming organ. Its real 

 nature, however, was not detected until the year 1856, when Schiff^ 

 proved that its total removal induces certain pathological conditions 

 which invariably prove fatal in the course of three to four weeks. In 

 spite of these perfectly definite results, the removal of this organ was 

 resorted to a number of times in subsequent years for the relief of 

 those serious respiratory difficulties which are usually associated 

 with goiter. In all these cases, this surgical procedure was followed 

 by very alarming symptoms which presented themselves chiefly as 

 disorders in nutrition and a general muscular weakness, tremors and 

 spasms.^ In 1884, Schiff operated upon a second series of sixty dogs 

 of which fifty-nine died within three weeks. This study drew renewed 

 attention to this organ, and spirited efforts were made henceforth to 

 unravel its function. Thus, it was soon discovered that the serious 

 symptoms following its total extirpation, could be prevented by per- 

 mitting a portion of, say, its lower extremity, to remain in the body.^ 

 Likewise, it was shown that the transplantation of the thyroid to some 

 other part of the body, such as the peritoneal cavity, protects the 

 animal against the consequences of thyroidectomy. The healing in of 

 these transplanted segments of the gland proceeds very quickly in 

 thyroidectomized animals so that their vascularization is practically 

 completed at the end of the third week. In the normal animal, on 

 the other hand, these transplants do not grow well and do not attain 

 this stage in less than eight weeks. ^ Lastly, Vassale^ proved that 

 the alarming effects of thyroidectomy may also be obviated by the feed- 

 ing of thyroid substance or the injection of thyroid extract. The 

 conclusion to be derived from experiments of this kind is that the 

 thyroid furnishes an agent which is absolutely essential to life. 

 The Symptoms Following .Th3n'oidectomy. — The effects of ex- 

 tirpation of the thyroid and parathyroids differ in different animals, 

 obviously because these structures vary in their size and position. In 

 the herbivora, for example, the parathyroids generally lie outside 

 the substance of the thyroid, while other animals are in possession of 

 accessory parathyroids which are scattered as small globular masses 

 along the trachea. In the fishes, these bodies are represented by small 

 patches of tissue of about the size of the head of a pin which are situated 



^ Swale Vincent, Ergebn. der Physiol., ix, 1911. 



2 Unters. iiber Zuckerbildung, Wiirzburg, 1859. Previous to this time we 

 have the experiments of Astley Cooper, Rapp and Bardeleben which, however, 

 led to no definite results. 



3 Reverdin (Rev. med. de la Suisse romande, 1882) ; Kocher (Archiv f iir klin. 

 Chir., 1883), and Billroth (Wiener med. Presse, 1877). 



* Eiselberg, Wiener klin, Wochenschr., v, 1892, 81. 



6 Salzer, ibid., 1909. 



« Neur. Zentralblatt, 1891. 



