318 PARATHYROIDS AND CALCIUM METABOLISM 



mus feeding had- been started, one of the larvae had a tetanic attack. 

 8 days after the beginning of thymus feeding the larvae were 

 transferred to a 1/1250 m solution of Ca lactate in tap water; this 

 suppressed tetanic convulsions up to the 7th week, while in the un- 

 treated controls tetany had started at the end of the 5th week. 

 Though the concentration of the solution was lowered to only 1/2500 m 

 Ca lactate, the tetany curve did not rise as it did in the controls, but 

 remained low until at the end of the 10th week. The concentration 

 of the solution was increased to 1/625 m, upon which the curve fell, 

 but soon it rose again and, after a further increase of the concentration 

 to 1/500 M, it fell to zero; this latter fall, however, is probably due in 

 part to the approach of metamorphosis, though the rise of the curve 

 soon after the commencement of metamorphosis was due to tetanic 

 convulsions of two larvae. 



As compared with the control thymus series the tetanic convulsions 

 in the Ca lactate series were doubtless somewhat decreased ; in par- 

 ticular it is very evident that an increase of the concentration re- 

 sulted in a fall of the curve. It is worth noting that in the Ca series 

 as in the untreated thymus series each single individual suffered 

 from tetanic convulsions though for a shorter period of its larval life 

 than the larvae of the thymus-fed, control series. 



The most important observation, however, is that though the mus- 

 cular convulsions were decreased by the action of the Ca salt, the 

 other symptoms of tetany, in particular the permanent paralysis of 

 almost the entire muscular system, developed at the same time 

 and with the same severity as in the untreated thymus-fed control 

 series. 



Finally, it should be mentioned that in the Ca series the metamor- 

 phosed animals behaved entirely differently from untreated thymus- 

 fed animals. When the larvae metamorphosed, they were taken out 

 of the solution and placed on moist filter paper. As in all other 

 thymus-fed animals, their muscles were paralyzed and the shape of 

 the body and of the legs was greatly deformed, abnormalities which 

 they had acquired during the tetanic period; like the untreated thy- 

 mus-fed animals, they did not suffer from tetanic convulsions. Sev- 

 eral weeks, however, after metamorphosis tetanic convulsions started 

 again in the Ca animals, in contradiction to what we have observed 



