i INTERNAL PROTECTIVE SECRETIONS 



the lowest portion of the thyroid body, as well as the inferior 

 parathyroids. 



Opinions differ at present as to the functional relation between 

 the thyroid and the parathyroids. Cley (1898) was inclined to 

 admit the existence of such an association between them, and 

 to think that the parathyroids prepared a substance which is 

 subsequently taken up and poured into the circulation by the 

 thyroids. According to Moussu, Vassale, and Generali, on the 

 other hand, the two glandular functions are independent and differ 

 specifically from one another. The thyroids have an essentially 

 trophic function, i.e. they secrete substances indispensable to 

 good general nutrition, particularly to the nervous and skeletal 

 systems ; the parathyroids, on the contrary, have an antitoxic 

 function, i.e. they neutralise or facilitate the elimination by the 

 kidneys of the toxic substances formed during metabolism. 



How, then, are we to explain the fact suspected by Vassale and 

 established by Lusena, to the effect that after simple parathyroid- 

 ectomy the convulsive nervous symptoms are more grave, and 

 lead more rapidly to a fatal issue, while after thyro-para- 

 thyroidectomy they are less serious and run a more protracted 

 course ? In order to account for this difference Lusena assumes 

 that in dogs deprived of the parathyroids only, the quantity of 

 toxic substances circulating in the blood is greater than that 

 circulating after complete thyro-parathyroidectomy. He believes 

 that the thyroids normally have the property of subtracting from 

 the blood the materia peccans of unknown character, to return it 

 transformed and innocuous ; and he holds this antitoxic function 

 of the thyroids to be dependent on the normal function of the 

 parathyroids, so that when the latter are removed a larger amount 

 of poison circulates in the blood. 



This bold hypothesis does not --it seems to us explain 

 the fact that the subsequent excision of the thyroids con- 

 spicuously attenuates the symptoms of tetany consequent on 

 parathyroidectomy. If, after removal of the parathyroids, the 

 thyroids are no longer capable of abstracting and transforming 

 the materia peccans in the blood, it is difficult to see why their 

 extirpation should diminish the symptoms of auto-intoxication. 



Vassale's theory is simpler, and suggests a better interpretation. 

 He holds the specific function of the thyroid gland to be that of 

 pouring into the circulation a secretion that excites and promotes 

 general metabolism. The myxoedenia consequent on functional 

 deficiency of the thyroid exhibits a complex of symptoms which 

 clearly indicate a reduction or perversion of the metabolic 

 exchanges, and the therapeutic action of thyroid juice or of 

 ingestion of thyroid in spontaneous or post-operative myxoedema 

 is characterised by phenomena of quickened metabolism. The 

 parathyroids, on the contrary, have a specific antitoxic function. 



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