PARATHYROID GLANDS 5 



If all four parathyroids are taken away, the animal 

 succumbs rapidly, with symptoms just such as have 

 been described under the heading of thyroidectomy, 

 tetany being a marked feature. The signs are the 

 same whether the thyroid gland is removed or left. 

 Leaving one parathyroid is usually sufficient to 

 prevent death, but tetany may still ensue. 



It would seem that in man, myxoedema is due to 

 loss of the internal secretion of the thyroid itself, 

 but that tetany and fatal symptoms in both man 

 and animals are due to loss of the parathyroids. 

 The convulsions of tetany in dogs may be arrested 

 by feeding on a watery extract of twelve to twenty 

 horses' parathyroids (Moussu). 



REMOVAL OF THYROID ALONE. 



Removal of the thyroid gland without the para- 

 thyroids is usually not fatal ; myxcedema results 

 in man ; occasionally, perhaps, in animals also, 

 but more commonly only cachexia. In young 

 animals, however, the results are much more distinct, 

 and Eiselsberg and others have induced very 

 convincing cretinism, with a remarkable stunting 

 of growth, in lambs, goats, rabbits, and asses. It 

 is interesting and important to notice that the 

 animals so treated developed exceedingly marked 

 atheroma of the aorta, of which Eiselsberg gives 

 good figures. 



THYROID FEEDING. 



We now turn to the effects of thyroid feeding in 

 the normal man and animal. These are perfectly 



