316 PARATHYROIDS AND CALCIUM METABOLISM 



exists and is contained in the thymus gland. ^ In the present article 

 certain experiments will be reported demonstrating that calcium is 

 able to suppress the tetanic convulsions, at least to some extent; the 

 writer, however, was unable to convince himself that this effect upon 

 tetany is characteristic for the calcium and furthermore the experi- 

 ments in question, though they do not exclude a possible relation 

 between the toxic substance and the calcium, prove conclusively 

 that, as far as the animals used in these experiments are concerned, 

 the tetany toxin, even in the presence of the calcium and in the ab- 

 sence of convulsions, brings about severe lesions of the muscular 

 system resulting probably from lesions of the central nervous system 

 caused by the tetany toxin and not prevented by the calcium. 



EXPERIMENTAL. 



In order to test the action of Ca lactate upon tetanic animals, a 

 number of larvae of the salamander Amby stoma opacum were fed on 

 thymus and kept at the same time in a solution of Ca lactate in ordi- 

 nary tap water; another set of larvae of the same age and from the 

 same female were kept in a solution of Mg lactate of the same con- 

 centration as the Ca lactate solution. A series of larvae from a dif- 

 ferent female, fed on thymus, but kept in ordinary tap water, served 

 as controls; since differences between larvse from different females as 

 regards the severity of tetany when fed on thymus are so small as 

 to be negligible, the error introduced by comparing larvae of different 

 females is very small. For each of the three thymus series one series 

 was kept as control, in which all conditions were the same as in the 

 thymus-fed series, except that small pieces of earthworms instead of 

 thymus served as food. None of the worm-fed control series de- 

 veloped tetany. 



I. Thymus-Fed, Untreated Controls (Fig. 1, Curve l). — ^Six larvae of 

 Ambystoma opacum were fed on thymus exclusively. As usual the 

 tetanic attacks began after the larvae had reached a certain develop- 

 mental stage^ and soon reached a maximum. Each single individual 

 came down with tetanic convulsions. When metamorphosis was 



3 Uhlenhuth, E., /. Gen. Physiol., 1918, i, 23, 33. 



