8 THE THYROID AND 



gland. This has been taken to prove that some 

 living organism is the effective cause, but another 

 theory is more probable, as we shall see later. 



In the earlier stages, parenchymatous goitre can 

 usually be cured, either by feeding on thyroid extract 

 or by means of potassium iodide. Marine* has 

 pointed out that in America there was formerly 

 a serious commercial loss in some districts from 

 cretin lambs, and that sheep and dogs with goitre 

 were numerous ; the substitution of an iodiferous 

 salt for pure rock-salt has been completely successful 

 in preventing all these manifestations. 



Chalmers Watson, and more recently Edmunds, 

 have obtained goitre in fowls by a meat diet. The 

 low iodine-content of the meat makes it necessary 

 for the thyroid to enlarge, so as to take the greatest 

 advantage of what iodine it can get. 



There is abundant evidence that iodides, and 

 especially organic combinations of iodine such as 

 iodoform, have great power in enhancing the 

 activity of the thyroid gland. We have 'already 

 seen that the gland normally secretes iodine in the 

 blood-stream, combined with a globulin. Roos, 

 and more recently Hunt and Seidel, have shown 

 that the activity of the colloid varies directly with 

 the amount of iodine contained in it. When iodides 

 or iodoform are given by mouth, they are taken up 

 by the thyroid and secreted in the blood-stream in 

 the form of iodothyrin, the normal active principle 

 of the gland. The amount of iodine in the gland 



* Johns Hopkins Hasp. Bull., 1907, xviii. p. 359. 



