PRODUCED BY ATROPIA IN COLD-BLOODED ANIMALS. 455 



Experiment XXXIII. — I injected into the abdomen of an active male frog, 

 weighing 251 grains, a solution of 03 grain of sulphate of atropia, in five minims 

 of distilled water. Flaccidity and motionlessness occurred rather more rapidly 

 than in the previous experiment ; and eight hours after the injection it was found 

 that the conductivity of the sciatic nerves was completely suspended — the muscles, 

 however, freely contracting when directly galvanised — and that the heart's action 

 was extremely feeble, and at the rate of only nineteen beats in the minute. 



On the following day — twenty-two hours after the administration — the heart's 

 impulse was even less apparent, and contractions occurred only seven times in 

 the minute ; while galvanism of the sciatic and brachial nerves was not followed 

 by any muscular contraction, although idio-muscular contractility was apparently 

 unaffected. 



The frog remained in this state of complete nerve-paralysis for other four 

 days. The cardiac action, however, improved during the latter portion of this 

 period, and on the sixth and seventh days the contractions occurred sixteen and 

 nineteen times respectively in the minute. 



On the seventh day — at about one hundred and forty-six hours after the 

 administration — a change occurred. The frog still lay on the abdomen and chest, 

 with the posterior extremities flaccidly extended ; but the anterior extremities 

 were now slightly arched, there were infrequent respiratory movements of the 

 throat, and a slight touch of the skin excited a feeble, momentary, and sudden 

 movement of the whole body. 



On the eighth day — one hundred and sixty-eight hours after the adminis- 

 tration — excitation produced a violent attack of tetanus, which was slightly 

 opisthotonic in character, and was succeeded, after lasting for eight seconds, by 

 a series of quivering movements of the posterior extremities. It was not neces- 

 sary, however, to apply excitation, in order to produce tetanic convulsions, for 

 they also frequently occurred when voluntary movements were attempted. At 

 one hundred and seventy hours, the tetanus was emprosthotonic. 



On the ninth day — one hundred and ninety hours after the administration — the 

 tetanic condition was exactly the same as at the latter part of the previous day. 

 and the frog remained extended horizontally for five seconds when lifted in that 

 position by the ankles. The heart was now contracting at the rate of twenty- 

 two beats in the minute. 



On the tenth day— two hundred and sixteen hours after the administration — 

 the frog was lying on the lower jaw, chest, and abdomen, the anterior extremities 

 being extended at right angles to the body, while the posterior were stretched 

 backwards. Excitation now caused a feebler and stiffer movement of the 

 limbs ; and however powerful the excitation, it was impossible to cause tetanic- 

 convulsions. 



On the eleventh day — two hundred and thirty-eight hours after the adminis- 



