866 PHYSIOLOGY OF DIGESTION AND SECRETION. 



little as 60 to 130 mgm. every three or four days. The first human 

 case treated in this way (Murray, 1891) was kept in good health 

 for twenty-eight years by the constant administration of thyroid 

 material. 



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 

 discovered 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 

 attracted attention to the parathyroids. Numerous experiments 

 by Moussu, Gley, Vassale and Generale, and others 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 

 usually described includes those cases in which both thyroids and 

 parathyroids were removed, while probably many of the apparentl}' 

 negative results obtained after excision of the thyroids are expU- 

 cable on the supposition that one or more of the parathyroids were 

 left in the animal. In spite of contradictory results in the hands 

 of some observers the general opinion prevails that complete 

 removal of the parathyroids in most mammals is followed by 

 acutely toxic results which develop rapidly, and the most common 

 symptom of which is muscular tetany. This tetany exhibits itself 

 as fibrillar contractions of the muscles, a general muscular tremor, 

 tonic and clonic spasms of the muscles or "intention spasms," 

 that is, spasmodic or uncoordinated contractions following upon 

 an effort to make a voluntary movement.* Macallum and 

 Voegthnf find that injection or ingestion of solutions of calcium 

 salts removes completely the symptoms of tetany and restores 

 the animal to an apparently normal condition. They have ob- 

 tained similar results upon human beings suffering from tetany 



* For literature and summary, see Bing, "Zentralblatt f. d. Physiol, u. 

 Pathol, d. Stoffwechsels," 1908, Nos. 1 and 2; also Biedl, loc. cit. 



t Macallum and Voegtlin, "Johns Hopkins Hospital Bulletin," March, 



