870 PHYSIOLOGY OF DIGESTION AND SECRETION. 



prevails that complete removal of the parathyroids 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 follow- 

 ing upon an effort to make a voluntary movement.* As is well 

 known, similar symptoms are often observed under other condi- 

 tions, infantile tetany, gastro-intestinal tetany, etc., and it has 

 been suggested that in all such cases the initial difficulty may 

 consist in the insufficiency of active parathyroid tissue. Several 

 observers have reported that injections of extract of the parathy- 

 roids cause the tetany to disappear without, however, protecting 

 the animal from a fatal outcome. Macallum and Voegtlinf 

 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 obtained simiJar 

 results upon human beings suffering from tetany as a result of 

 unintentional removal of the parathyroids. The experimental 

 evidence in the case of the parathyroids tends to support the 

 view that their function consists in neutralizing in some way 

 toxic substances formed elsewhere in the body, and that, therefore, 

 after removal of these glands death occurs from the accumulation 

 of such toxic bodies in the blood and tissues. Thus Macallum 

 states that in animals in which tetany has developed as a conse- 

 quence of extirpation of the parathyroids, bleeding and infusion 

 of salt solution causes the tetany to disappear. The results 

 quoted above in regard to the therapeutic value of calcium salts 

 would seem, moreover, to connect the parathyroid function with 

 the calcium metabolism and to relate the development of toxic 

 substances with an insufficiency of calcium, but at present no 

 precise statement can be made in regard to the way in which 

 these bodies perform their very important function. The view 

 that the parathyroids are simply immature thyroid tissue is still 

 supported by some observers, being based chiefly on the his- 

 tological finding that after removal of the thyroids the para- 

 thyroids may hypertrophy and show thyroid cysts containing 

 colloidal material. Most observers, however, take the view 

 outlined above, that the parathyroids have a functional signifi- 

 cance essentially different from that of the thyroids, and that the 

 parathyroids as they exist in the body are not simply undeveloped 



* 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, 

 1908. 



