THE THYROID AND PARATHYROIDS 303 



often be observed in unoperated animals. He states that 

 out of four monkeys operated on in England one was 

 sent to him as " myxoedematous." The animal had nothing 

 more than an ill-defined facial swelling, probably due to 

 a carious tooth, and an intermittent paresis of a fore 

 limb. The animal was, according to Munk, otherwise in good 

 health and lived for ten months after the operation. Munk 

 insisted that although removal of the thyroid is a dangerous 

 operation, it does not follow that the thyroid is absolutely 

 essential to life. And this statement must be admitted as 

 justifiable, even if the survivals are due to thyroid or parathy- 

 roid tissue which is so placed that it cannot be removed. It 

 will be necessary to return to this point. 



The further account of Gley's work, as well as that of Vassale 

 and Generali and Kohn, will be found in the section on the 

 physiology of the parathyroids. 



The experiments of Vincent and Jolly may be briefly recalled 

 so far as they relate to the general question of extirpation of 

 thyroids and parathyroids, and more particularly in regard to 

 the effects alleged to be due to elimination of the function of 

 the thyroid. On these points the general conclusions were : 

 " Neither thyroid nor parathyroids can be considered as organs 

 absolutely essential for life. Rats and guinea-pigs do not seem 

 to suffer at all as the result of extirpation. Monkeys show 

 only transient nervous symptoms. Dogs, cats, foxes and 

 prairie wolves frequently suffer severely and die. On the other 

 hand, badgers do not appear to be affected by the operation. 



" In no animals, not even in monkeys, have we been able to 

 induce any swellings of the subcutaneous tissue, which is the 

 most striking feature of myxcedema in the human subject. We 

 think, therefore, that the pathology of myxoedema must be 

 more complex than simple thyroid insufficiency." l 



Several previous observers from Schiff onwards had noted 

 the fact that thyroidectomy in dogs and cats is by no means 

 always fatal. At the same time there has been a tendency to 

 disregard the exceptions, and, when any explanations have 

 been offered it has been suggested that they are due to parathy- 

 roids having been overlooked at the operation, or to the exist- 

 ence of accessory thyroids. Munk (vide supra) indeed is among 



1 On other points discussed in these papers the present writer has changed 

 his opinion. This applies to the change of parathyroid into thyroid. 



