176 THE DISEASES OF THE PARATHYROID GLANDS 



and fourth branchial pouch. The thymus gland comes from the ventral part 

 of the third pouch. 



If the bilaterally arranged thymus gland becomes pushed down the para- 

 thyroids may come to rest on the thymus gland or even to be included in its 

 substance. From the illustration it will be also seen that the relationship 

 of the parathyroids to the thyroid is purely topographical. _E 4 represents 

 the inner parathyroid gland which may eventually become included in the 

 tissue of the thyroid. 



Historical. It will be seen from the intimate spatial relationship between 

 the thyroid and the parathyroids why for a long time the functional inde- 

 pendence of the parathyroids was not recognized. As a sequence of the 

 first attempts at total thyroidectomy, by Schiff, Kocher, Rivardin, v. Eisel- 

 berg and others, there were observed, in addition to the results of the absence 

 of the thyroid as described in Chapter II, severe acute manifestations that 

 were uncommonly like the tetany that had formerly been observed in 

 human pathology. The difference in topography of the parathyroids in 

 different animal species, as just described, makes intelligible why in some 

 species thyroid extirpation led to cachexia strumipriva, in others to tetany. 

 The discovery of the parathyroids, in 1880, by Sandstrom, first made a 

 change in this respect. Indeed Sandstrom at first regarded the bodies described 

 by him as the embryonal stages of thyroid tissue that had remained at a 

 standstill; Gley, who in 1891 first discussed the physiological significance of 

 the parathyroids, believed that these bodies would assume the function 

 of the thyroid on extirpation of that gland. A. Kohn first taught the 

 anatomical independence of the parathyroids; Moussu, and Vassale and 

 Generate their functional independence. Kohn also introduced the term 

 "Epithelkorperchen." The investigations of Pineles, Biedl, Erdheim and 

 others to-day place the independence of the parathyroids beyond question. 

 The observations of aplasia of the thyroid with retention of the parathyroids, 

 as detailed in chapter on the thyroid, showing the complete picture of 

 deficiency of the thyroid with no symptoms whatever of tetany, further 

 the fact that the absence or deficiency of thyroid gland only, not however 

 that of the parathyroids, is made good by thyroidin therapy, and finally the 

 fact established in animal experimentation that extirpation of the para-^ 

 thyroids alone leads to tetany but not to myxedema, make certain the 

 teaching of the physiological independence of the parathyroids and have furnished 

 the demonstration that tetany has nothing to do with the absence of thyroid 

 gland, but depends on an insufficiency of the function of the parathyroids. 



It is only one step from this knowledge to the view that the different forms 

 of tetany observed in human pathology (parathyroprivic tetany), idiopathic 

 or occupation tetany, tetany of children, tetany of maternity, stomach 

 tetany, tetany in infectious diseases and poisonings, etc., depend on a 

 uniform pathological basis, and that at the bottom of all is an absolute or 



