IODINE IN THE ANIMAL ORGANISM. 455 



chloride and phosphoric acid. The rise in sodium chloride 

 does not last as lono- as the others. 



In dogs without a thyroid, the increased excretion of 

 nitrogen and chlorine is even more marked, while that of 

 phosphoric acid is not so great as in healthy animals. 

 There is also a diuretic action. 



Some attempts were made to separate and identify the 

 active substance of the thyroid, but this part of the research 

 was incomplete. So far as the experiments went they 

 showed that the material is very stable ; this was previously 

 known because good effects follow thyroid feeding ; the 

 substance is therefore one which is not altered to any extent 

 by digestive processes. The substance is probably proteid- 

 like in nature, though not an enzyme as Notkin 1 considers. 



This conclusion fits in very well with some previous 

 work done by Gourlay. 2 Gourlay separated a nucleo- 

 proteid and an albumin from the thyroid ; he further 

 discovered that the colloid matter in the thyroid vesicles is 

 nucleo-proteid and if this passes into the lymphatics, as 

 some have described, he thought it possible that the nucleo- 

 proteid was the active agent. This contains nuclein, a 

 substance not affected by gastric digestion. 



Later Frankel 3 separated from the thyroid a crystalline 

 material which he named thyreo-antitoxin ; this has the 

 formula C 6 H n N 3 5 ; the evidence that this is really what 

 its name signifies cannot, however, be described as satis- 

 factory. 



E Baumann 4 continued the search, and it was here that 

 he came across the substance he called thyro-iodin, which 

 is remarkable among animal products in containing iodine. 

 The glands were boiled for days with ten per cent, sulphuric 

 acid ; the liquid after cooling deposited a glocculent pre- 

 cipitate, which after extraction with alcohol is the substance 

 in question. It contains 9/3 per cent, of iodine, and it may 



1 Wiener med. JVoche?isch., No. 19 and 20, 1895. Notkin named the 

 enzyme he supposed to be the active agent — thyreo-proteid. 



2 /ourn. of Physiol, xvi., p. 23. 3 Wiener med. Blatter, No. 48, 1895. 

 4 Zeit. physiol. Chew., xxi., p. 319, 1895. 



