458 THE DUCTLESS GLANDS. 



thyroids that are free from colloid, such as parenchymatous goitres 

 and the glands of the newborn. Oswald concludes that the thyreo- 

 globulin is only iodized after it leaves the follicle-cells. At the 

 same time it is noteworthy that non-iodized thyreoglobulin alone 

 never leaves the cells, but only if iodo thyreoglobulin is simultane- 

 ously secreted. The amount of iodine hi a gland can be artificially 

 increased by the ingestion of iodine or iodides as such, and it is to 

 be noted that the physiological activity of the gland can thus be in- 

 creased, while this is not possible by iodizing the thyreoglobulin in 

 vitro. 



The existence of a non-iodized thyreoglobulin 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. 



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 with 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. On further 

 decomposition it loses its activity altogether. 



Thyreo-nucleoproteid. A nucleoproteid is found in associa- 

 tion with thyreoglobulin in the colloid material of the gland, but 

 is present in much smaller amounts ; it contains 0.16 per cent, of 

 phosphorus. In a 10 per cent, solution 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 ammonium sulphate to saturation. 



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



