SECRETION OF THE DUCTLESS GLANDS. 773 



mental development designated as cretinism, and in the adult the 

 same cause gives rise to the peculiar disease of myxedema, character- 

 ized by distressing mental deterioration, an edematous condition 

 of the skin, loss of hair, etc. Schiff and others found that the evil 

 results of complete thyroidectomy in dogs might be obviated by 

 grafting pieces of the thyroid in the body, and this knowledge was 

 quickly applied to human beings in cases of myxedema and cretinism 

 with astonishingly successful results. Instead of grafting thyroid 

 tissue it was found, in fact, that injection of extracts under the 

 skin or better still simple feeding of thyroid material gave similar 

 favorable results: the individuals recovered their normal appear- 

 ance and mental powers.* Later Baumannf succeeded in isolating 

 from the glands a substance designated as iodothyrin, which shows 

 in large measure the beneficial influence exerted by thyroid extracts 

 in cases of myxedema and parenchymatous goiter. This substance 

 is characterized by containing a large amount of iodin (9.3 per 

 cent, of the dry weight). It is contained in the gland in combina- 

 tion with proteid bodies, from which it may be separated by diges- 

 tion with gastric juice or by boiling with acids. 



The Function of the Parathyroids. Most of the results des- 

 cribed above were obtained before the existence of the parathy- 

 roids was recognized. Early in the history of the subject it was 

 recognized that complete removal of the thyroids proper in herbiv- 

 orous animals (rats, rabbits) is not attended by a fatal result. 

 Gley and others, however, proved that if the parathyroids also are 

 removed these animals die with the symptoms described in the 

 case of dogs, cats, and other carnivorous animals. This result at- 

 tracted attention to the parathyroids. Numerous experiments, 

 especially by Moussu,t Gley, and Vassale and Generate, || have 

 seemed to show a marked difference between the results of thyroi- 

 dectomy and parathyroidectomy. When the parathyroids alone are 

 removed the animal dies quickly with acute symptoms, muscular 

 convulsions (tetany), etc.; when the thyroids alone are removed 

 the animal may survive for a long period, but develops a condition 

 of chronic malnutrition, a slowly increasing cachexia which may 

 exhibit itself in a condition resembling myxedema in man. This 

 distinction has been generally accepted, and it throws much light 

 upon the discrepancy in the results obtained by some of the earlier 

 observers. Complete thyroidectomy with the acutely fatal results 



* For a general account of the development of the subject and the liter- 

 ature see " Transactions of the Congress of American Physicians and Surgeons" 

 (Howell, Chittenden, Adami, Putnam, Kinnicutt, Osier), 1897, and Jean- 

 delize, " Insuffisance thyroidienne et parathyroidienne, " Nancy, 1902. 



t "Zeitschrift f. physiolog. Chemie," 21, 319, and 481, 1896. 



% Moussu, " Proc. Fourth International Physiolog. Congress, " 1898. 



Gley, "Pfliiger's Archiv," 66, 308, 1897. 



|| Vassale and Generate, " Archives italiennes de biologie, " 33, 1900. 



