I 



CENEItAL ACTION OK FHOGS AND CATS. . 475 



tAvo the restlessness subsided and gave place to lethargy, the 

 frogs showing a great disinclination to move, and allowing 

 themselves to be gently pushed along the table without jump- 

 ing. The respiration still continued rapid. In about two 

 minutes more (generally three to five minutes after the injection 

 of the poison) the frogs gave a sudden spring, and fell into 

 tetanic convulsions. Tliese lasted about half a minute, and then 

 became more or less relaxed ; they soon returned, however, and 

 continued to do so at nearly regular inter\'als, when the frogs 

 weve left alone, but they might also be brought on by touching 

 the animals. When the relaxation of the muscles was imper- 

 fect, so that the le^s still remained extended durino- the inter- 

 vals, the convulsions were marked by twitchings of the toes. 

 In some instances the mouth seemed to be the part first 

 affected by the convulsion, as the jaws were seen to open and 

 sluit, although it is possible that this was connected with respi- 

 ration rather than with the generah convulsions; next the arms 

 were affected, and lastly the legs. The arms seemed also to be 

 more sensitive tlian the legs, as slight spasmodic twitches 

 could sometimes be produced by touching or pinching the arms, 

 when similar irritation of the legs had no effect. After con- 

 tinuing for some time the convulsions became gradually weaker, 

 and the animal died. 



General Action on Cats. — The only w^arm-blooded animals on 

 which we have as yet experimented with nitro-glycerine are 

 cats, and although it is probable that a general similarity exists 

 between its action on these and on other mammalia, yet it is 

 not unlikely that there are minor differences which can only 

 be ascertained by farther experiments. On injecting 4 cubic 

 centimetres of a 10 per cent, solution into the peritoneal cavity 

 of a cat, the first symptom noticed two minutes after the injec- 

 tion was a stretching movement of the hind leg, as if the 

 animal were trying to shake something off the foot. In about 

 half an hour the cat cried as if in uneasiness or pain, and then 

 vomited. In about half an hour more the legs seemed to fail 

 during walking, and the animal suddenly sank down and never 

 again rose. Vomiting again occurred once or twice, the respira- 

 tion becoming exceedingly rapid (120 per minute), and the 



