434 THE DUCTLESS GLANUS. 



The iodine, however, is manifestly not a constant component of 

 the globulin, and may be absent altogether. This is especially 

 interesting in view of the fact that, whereas the iodized globulin 

 possesses all the specific properties of the entire gland, the non- 

 iodized substance is inert. An adequate explanation of this curious 

 phenomenon cannot at present be given, but we may imagine that 

 in those instances in which the iodine is normally absent its place 

 may be taken by some other halogen, or a compound halogen which 

 has escaped observation. To conclude that the iodized substance 

 is not the active principle of the gland, on the basis that the 

 glands of some animals contain no iodine, and that its amount is 

 more or less variable and can artificially be increased, is scarcely 

 warrantable. It is conceivable that in sucklings, for example, in 

 which iodine is commonly absent, a compound halogen takes its 

 place, and is, for the time being at least, fully capable of preventing 

 the development of the complex of symptoms which we term ca- 

 chexia strumipriva. Further researches, however, are necessary to 

 explain satisfactorily the apparent contradiction. The fact that the 

 thyreoglobulin of those glands in which it is especially abundant 

 contains a relatively smaller amount of iodine than others in which 

 less globulin is present, can readily be explained on the basis that 

 the total amount of iodine is here distributed over a larger quantity 

 of the globulin, and, as has been stated, the absolute amount is here 

 larger than in normal glands. 



In its general properties thyreoglobulin resembles the common 

 globulin of the blood. It differs, from this, however, in the fact 

 that it is precipitated from its saline solutions on the addition of 

 dilute acids. In this respect it resembles the myosin of muscle- 

 tissue. Its point of coagulation, in a 10 per cent, solution of mag- 

 nesium sulphate, varies between 65 and 67 C. It is precipitated 

 from its solutions by the addition of an equal volume of a saturated 

 solution of ammonium sulphate. 



On decomposition \vith dilute acids it yields the thyroiodine of 

 Baumann, but contains more iodine, viz., 14.29 per cent,, and, like 

 its mother-substance, it is free from phosphorus. 



Thyreo-nucleo -albumin. The nucleo-albumin which, as I have 

 stated, is found in association with thyreoglobulin in the colloid 

 material of the gland, but is present in much smaller amounts, 

 contains 0.16 per cent, of phosphorus. In a 10 per cent, solu- 

 tion of magnesium sulphate it coagulates at 73 C. On digestion 

 with gastric juice a nuclein is split off, which contains xanthin- 

 bases. The substance is free from iodine, and is physiologically 

 inert. It is precipitated from its solutions by salting with am- 

 monium sulphate to saturation. 



For a further description of the two albumins, and of the 

 methods which may be employed for their isolation, I must refer 

 the reader to Oswald's paper. 1 



1 Zeit. f. physiol. Chem., vol. xxvii. p. 14. 



