228 



SWALE VINCENT 



thyroids deep not produce the train of symptoms terminating fatally, must 

 in" the light of the work of other investigators be explained as due to a 

 failure to remove all the parathyroid tissue." Now, in the case of rabbits, 

 Paton quotes Pepere to the effect that accessory parathyroids are nearly 

 always found in the thymus in rabbits. So that in rabbits parathyroid- 

 ectomy is only fatal in the few animals which happen not to have any 

 parathyroid tissue in the thymus. 



In the monkeys employed by Vincent and Jolly no symptoms of 

 myxedema were observed when thyroids and parathyroids were completely 

 . , removed. These results dif- 

 fer from those obtained by 

 Horsley (loc. cit.), Murray 

 (c) and Edmunds (a.)? wno 

 state that it is possible to 

 induce myxedema by opera- 

 tion. Compare with the re- 

 sults obtained by Munk 

 (vide supra) and Kishi. 

 The last-named only re- 

 corded one death out of six. 

 Our animals were subject to 

 catarrh, and one died of 

 some laryngeal affection, 

 and it seems probable that 

 as in the case of other ani- 

 mals, removal of the thyroid 

 gland leaves monkeys in a 

 condition in which they are 

 less capable of resisting dis- 

 ease. Most of the animals 



were active, and but for loss of weight showed no ill effects. In con- 

 firmation of the results of Vincent and Jolly, observers have failed to 

 find any trace of a myxedematous condition in such animals. 



Carlson and Woelfel report that myxedema does not develop in thyroid- 

 ectomized rabbits, at least in seven months, nor in the monkey in several 

 months. 



In some groups of animals age seems to make a great difference to 

 the results both of thyroidectomy and of "complete" thyroparathyroid- 

 ectomy. Sutherland Simpson found that removal of the thyroid with the 

 contained internal parathyroids in thirteen adult sheep and sixteen lambs 

 from seven to eight months old, led to practically no ill effects (see Fig. 1). 

 As a result of a similar operation, three lambs about two months old 

 became "typical cretins" (see Fig. 2). 



Fig. 1. Photograph of a group of thyroidecto- 

 mized sheep taken five months after operation 

 (after Simpson, Quart. J. Exper. Physiol. ). 



