522 SUTHEKLAKD SIMPSON 



roids, which have been inadvertently left behind. Parathyroid tissue is 

 said to occur frequently in the thymus. Harvier (1909) found it so in 

 fifty per cent of all the cats he examined, and Marine (1914) in five or 

 six per cent of dogs. Pepere (&) (1907), who upholds the theory of a 

 separate and important function for the parathyroid, found small bits of 

 parathyroid tissue in the thymus of nearly all rabbits. 



MacCallum adheres to the theory of Gley and of Vassale and Generali 

 that the parathyroids are vitally essential. He says: "At least we know 

 well that the destruction of all the parathyroid glands results in the death 

 of the animal with symptoms of tetany, which is not in the least dependent, 

 as was once taught, upon the destruction of the thyroid gland." His own 

 experiments and those of others have convinced him, beyond doubt or 

 question, of the correctness of this view. Again, MacCallum and Voegtlin 

 (1909) state that "the fact appears to be thoroughly well established, in 

 spite of the dissenting voices of a few English investigators, that the para- 

 thyroid glands are organs of independent nature, and not developed from 

 the thyroid or convertible into thyroid tissue. The evidence against this is 

 of so insignificant a character, as compared with the overwhelming evi- 

 dence in its favor, that space need not be occupied here in discussing it." 



Paton and Findlay (b) say: "The clearest evidence that the structures 

 are not identical is the fact that the removal of the parathyroids produces 

 tetany, and removal of the thyroid does not do so ; and this being the case, 

 it seems unnecessary to give further consideration to a theory which has 

 been amply refuted by adequate experimental evidence from many differ- 

 ent sources. Our experience only confirms the conclusions arrived at by 

 these former workers, Nothing can be more convincing than to remove all 

 the thyroid tissue along with the parathyroids leaving one external 

 parathyroid with its blood supply intact. Generally no symptoms at all, or 

 at most transient tremors supervene, and only when the remaining para- 

 thyroid is removed does true tetany develop." It should be remembered 

 that both MacCallum and Paton worked mainly with dogs and cats. 



Evidence That Parathyroidectomy May Produce No Symptoms. In 

 the course of the last twelve years the writer has performed the complete 

 operation on upwards of one hundred dogs, and, with one possible excep- 

 tion, in which no opportunity of observing the effect was available, every 

 one of these animals was seized with the symptoms of acute, postoperative 

 tetany within a few days after the operation (one in twelve hours) ; many 

 of them died, and to the others the extirpation would probably have proved 

 fatal, if they had not been purposely killed by an overdose of chloroform in 

 the acute stage. This is probably an unusual experience, since there are 

 few records in the literature of series of thyroparathyroid extirpations 100 

 per cent successful, judged by the fact that tetany always followed, even 

 in the dog. In view of these results, he was perfectly convinced of the 

 truth of the Gley theory, viz., that complete parathyroidectomy is always 





