io8 The Iodine Complex of Thyreoglobulin 



shown to be present in every case tested. In this connection it 

 may be mentioned that the results in series VI are of no value. 

 This series VI, however is an illustration of irregular results, due 

 in all probability to impure acetonitrile. The acetonitrile was 

 taken from a freshly opened bottle and found to smell decidedly 

 of hydrocyanic acid. Before using, it was shaken twice with 

 saturated potassium carbonate solution, dehydrated with P 2 O 6 

 and twice distilled from fresh P 2 5 . Finally it was redistilled and 

 the fraction collected between 79 and 83C. This distillate was 

 used in series VI. For the later series this distillate was again 

 purified in the same way three times and finally redistilled twice 

 without the addition of P 2 O 6 . Here the distillate was collected 

 between 80.5 and 81.5C. 



Secondary albumose. This is much less active per unit of iodine 

 than either the iodothyrin preparations or the primary proteoses. 

 Series VII shows this, where the maximum dose resisted is only 

 40 per cent of the maximum dose resisted by the thyroid-tissue 

 fed mice. 



Ammo-acids from the phosphotungstic acid precipitate and the 

 phosphotungstic acid filtrate respectively. The results in series IX 

 indicate that the former possess very little physiological activity 

 as measured by the Hunt method. On the whole, however, the 

 results here are very unsatisfactory as the mice did not eat the 

 amino-acid mixtures well, there being two or more days' feeding 

 left. The results indicate that these amino-acid fractions contain 

 very little thyroid activity. This is better shown in series X 

 where only one-tenth the quantity of iodine-containing substances 

 was fed. Although the mice fed with dried thyroid tissue resisted 

 an amount over two and a half times that of the control mice, still 

 the mice fed with the same amount of iodine, but in the form of 

 amino-acids, resisted very little, if any, more of the acetonitrile 

 than the control mice. In other words, these amino-acid fractions 

 show a very slight physiological activity, if indeed they possess 

 any activity whatever. 



Tetra-iodohistidine anhydride and iodotryptophane. These sub- 

 stances when fed in amounts representing ten times the amount 

 of iodine fed as thyroid tissue do not appreciably increase the 

 resistance to acetonitrile. See series II and VIII. 



