29 



The salutary effect, both of injection of thyroid juice and of 

 thyroid ingestion by the mouth, is probably owing to the fact that 

 it facilitates the elimination of the toxic products accumulated in 

 the blood. In this connection the following observation of Vassale 

 is interesting : " After the injection of thyroid juice," he wrote in 

 1892, "the animal as a rule drinks water, sometimes in very large 

 quantities ; it subsequently excretes an excessive amount of urine, 

 after which it returns to its normal condition, and remains well 

 for at least twenty-four hours. It seems as though the animal 

 drinks much water in order, with the large amount of urine it 

 then evacuates, to wash the body free of a toxin that had previously 

 accumulated in the blood and tissues." This gives weight to our 

 hypothesis that the thyroid secretion normally has the function of 

 directly or indirectly exciting renal secretion. 



The work of Godard and Slosse, carried out under Heger's 

 direction, also supports this point of view. According to these 

 experiments, the thyroid juice has a lymphagogic action, analogous 

 to that exhibited by the lymphagogues of Heidenhain's second 

 category (Vol. I. p. 523 et seq.\ which indirectly promote diuresis 

 by transporting water and the products of katabolism into the 

 lymphatic sinuses and vessels and the blood. 



From the physiological point of view these results show that 

 the protective action of the thyroid depends on the specific 

 character of the chemical substances which it contains, and which 

 normally pass into the blood by continual internal secretion. 

 Many workers have therefore devoted themselves to research in 

 this direction by chemical analysis of the thyroid juice. Their 

 results are interesting, though inadequate for the solution of this 

 difficult problem. 



Notkin (1895) prepared a special substance from calf's thyroid 

 which he termed thyreo - protein ; this on injection into a dog 

 recently deprived of its thyroid induced phenomena of tetany 

 that subsequently ceased, to reappear at each fresh injection. He 

 concluded that it was this substance (normally retained by the 

 thyroid and rendered innocuous) which causes the auto-intoxica- 

 tion consequent on thyroidectomy. In addition to thyreo-protein . 

 Notkin isolated another indefinite substance from thyroid extract 

 which he termed thyreo-gummin ; this acts upon the former and 

 transforms it into an innocuous substance, necessary to the nutrition 

 of the body. He was in fact able to neutralise the noxious effects 

 of thyreo-protein by simultaneous injection of thyreo-gummin. 

 These very suggestive results have not, so far as we know, been 

 repeated or confirmed by other workers. 



Frankel simultaneously affirmed that the active principle of 

 the colloid substance, or secretion, which the thyroid pours into 

 the lymph and blood system, is a mucin, which he obtained from 

 the watery extract of boiled and filtered thyroid. He called it 



