THE PAKATHYROID GLANDS 547 



not all frog's muscle preparations were responsive, and this biological test, 

 on that account, is not entirely reliable. In certain cases, however, the 

 serum acts upon the muscle in the same way as do dilute solutions of guani- 

 din and methylguanidin. An example is seen in Figs. 8 and 9. After 

 seventeen minutes' immersion in the serum of a cat which had been show- 

 ing marked symptoms of parathyroid tetany for three days, a frog's gas- 

 trocnemius gave spontaneous twitchings, recorded in the upper tracing of 

 Fig. 8. This figure shows the gradual development of the spontaneous 

 muscular contractions. Frequently, when a single stimulus was applied 

 to the muscle immersed in the serum, a simple muscle twitch was obtained, 

 but it was markedly prolonged, resembling the complete tetanus of frog's 



Fig. 8. Showing the gradual development of tremors or spontaneous contraction 

 in the frog's gastrocnemius in serum from the blood of parathyroidectomized cat. 

 Time in sees. (Wishart.) 



muscle (Fig. 9). The serum of normal dog's and cat's blood caused no 

 such tremors or prolonged contractions. Burns studied nitrogen elimina- 

 tion in dogs after guanidin administration and after parathyroidectomy, 

 and found that the results showed a marked similarity. Following the ad- 

 ministration of guanidin the excretion of nitrogen was increased immedi- 

 ately and out of all proportion to the dose, while the ratio of urea nitrogen 

 to total nitrogen was decreased. The ammonia excretion was slightly de- 

 creased in feeding animals and showed a slight increase in animals that 

 refused food. The excretion of creatinin showed only a very slight in- 

 crease, if any at all, and the percentage of undetermined nitrogen rose 

 markedly immediately after injection of guanidin. In every respect the 

 protein metabolism of parathyroidectomized animals is very similar to 

 the above. 



Burns and Watson (a) (1920) found that guanidin intoxication and 

 parathyroid tetany, in many respects, have a similar effect on the heart and 



