320 PARATHYROIDS AND CALCIUM METABOLISM 



convulsions. And two of the animals which did not have convulsions 

 during their larval period had convulsions after metamorphosis. But 

 the third specimen, which had no convulsions during its larval life, 

 never had tetanic convulsions; it was still alive 43 weeks after 

 metamorphosis. 



DISCUSSION AND CONCLUSIONS. 



The experiments reported in this article are in full agreement with 

 the facts known about the action of Ca and Mg salts in tetanic ani- 

 mals. In the concentrations used here both Ca lactate and Mg lac- 

 tate suppressed the muscular convulsions in the tetanic salamander 

 larvae. The Mg lactate, however, appears to be more effective 

 than the Ca lactate. At any rate the suppression of the tetanic 

 convulsions does not seem to be a specific action of the calcium. 



The most important result seems to be the fact that the salts used, 

 though they prevented the muscular convulsions, did not prevent the 

 other symptoms of tetany which in the salamander larvae are very 

 definite and constant. The permanent spasmodic contractions and 

 the paralysis of the muscles developed in spite of the presence of the 

 Ca and Mg. Furthermore, the muscular contractions and the 

 paralysis developed even in such thymus-fed animals in which the 

 convulsions had been suppressed completely; this was the case in 

 one of the animals of the Mg series. 



From the experiments of BiedP and others it is likely that the 

 tetanic convulsions are due to lesions of the central nervous system, 

 since convulsions of a leg can be prevented by isolating it from the 

 central nervous system by cutting the nerves which connect the 

 muscles with the central nervous system. Evidently these lesions of 

 the central nervous system are the chief factor in tetany, while the 

 convulsions of the muscles are only an effect. In the larvae of sala- 

 manders these lesions find a definite expression in the permanent 

 paralysis of almost the entire muscular system. 



In the writer's opinion, MacCallum's hypothesis that the tetany 

 toxin has a special affinity for Ca, thereby diminishing the Ca con- 

 tent of the organism, cannot be disproved at present. But the 



^Biedl, A., Innere Sekretion, Beriin and Vienna, 1913, i, 126. 



