90 THE BODY AT WORK 



of potassium given internally, and tincture of iodine as an 

 outward application, were the approved remedies. It is now 

 known that myxcedema and certain forms of goitre may be 

 checked, and even cured, by administering uncooked thyroid 

 gland or even tabloids of dried extract. Fortunately, it is not 

 necessary to inject it subcutaneously ; the iodine-containing 

 compound is so stable as to resist the action of gastric juice. 



Iodine stored in the thyroid and parathyroid glands is 

 distributed to all the tissues. The remarkable symptoms 

 which indicate that the tissues are not receiving an adequate 

 supply may occur under either of two conditions. Iodine may 

 be deficient in the food, or the thyroid gland may be incom- 

 petent ; the former is the commoner cause. And here we see 

 the explanation of the formation of a goitre. By increasing 

 the size of the organ which selects iodine, Nature attempts to 

 obtain and store an adequate supply for distribution to the 

 tissues. 



Cretinism has been observed in animals. If attention were 

 directed to this inquiry, it might be found that it is not so 

 exceedingly rare as would be judged from the few observa- 

 tions that have been recorded. A cretin, if a wild animal, 

 falls an easy prey. If a domesticated animal, little trouble 

 is taken to insure its survival. A myxcedematous pig is a 

 dwarf with coarse, sparse hair, thick, warty hoofs, large jowl, 

 heavy ears. It is apathetic. A piglet presenting these charac- 

 teristics is not altogether uncommon in a litter. Among 

 chickens and pigeons, also, individuals appear which might, 

 judging from their uncouth appearance and mental dulness, 

 be suffering from cretinism. The only way of proving that 

 this is the case is to feed them on thyroid glands ; it does 

 not matter from what animal the gland is obtained. Opera- 

 tive cretins, produced by removing the thyroid gland soon 

 after birth, recover their natural characters on a diet contain- 

 ing a daily allowance of thyroid gland. The coarse hairs, or 

 wiry towsled feathers, fall off, and are replaced by a smooth, 

 supple growth. The thickened skin becomes soft and pliant. 

 Mental apathy gives place to alertness. They make up for 

 lost time by growing more rapidly than other animals of the 

 same age, which have not been operated upon, although they 

 never surpass the normal stature. 



