CHEMICAL CONSTITUTION AND PHYSIOLOGICAL ACTION. 703 



stimulation of the skin of the poisoned region caused no movement whatever, but 

 feeble movements could still be excited in both poisoned and non-poisoned regions 

 by strong stimulation ; and the sensibility of the non-poisoned region was in much 

 the same condition. In one hour and forty-five minutes, it was impossible to 

 excite any reflex movement whatever. Galvanic stimulation of the right (non- 

 poisoned) sciatic nerve was followed by vigorous movements restricted to the 

 right leg ; and, when this stimulation was applied to the left (poisoned) sciatic 

 nerve, similar movements were produced in the left leg, and nowhere else. The 

 heart was now contracting at the rate of twenty beats per minute. This state of 

 suspension of the reflex function, with retention of conductivity in the motor 

 nerves and of contractility in the muscles, continued until at least three hours 

 after the administration of the poison, when the observations were interrupted. 

 On the following morning, it was found that the conductivity of the poisoned 

 sciatic nerve was suspended, while the poisoned muscles contracted when directly 

 stimulated by an interrupted current. The conductivity of the non-poisoned 

 sciatic nerve was still retained. 



We learn from this experiment, that although a large dose of atropia quickly 

 produces in frogs a condition of marked paralysis, the conductivity of the 

 sensory and motor nerves and the reflex function of the spinal cord are not 

 completely suspended until considerable intervals after the administration. Of 

 these special paralytic actions, that on the motor nerves appears to be the last to 

 be effected ; indeed, in this experiment an interval of least an hour and fifteen 

 minutes elapsed between the complete suspension of the reflex function and that 

 of conductivity of these nerves. 



We shall now endeavour to discover if the salts of the methyl derivative of 

 atropia produce their paralytic symptoms by the same actions as atropia does. 



Experiment XLIII. — Having ligatured the artery and veins at the upper 

 third of the right thigh °of a frog that weighed 235 grains, we injected under 

 the skin of the left flank one-tenth of a grain of sulphate of methyl-atropium, in 

 four minims of distilled water. Paralytic symptoms followed with great rapidity : 

 so that in five minutes and thirty seconds, the frog was motionless, excepting that 

 vigorous spontaneous movements frequently occurred in the right (non-poisoned) 

 posterior extremity; and stimulation of the skin of any part, even though severe, 

 did not produce the faintest muscular contraction in the poisoned region, although 

 it produced strong contractions in the non-poisoned {right) posterior extremity. 

 In six minutes, it was ascertained that the heart was contracting at the rate of 

 forty beats in the minute. Frequent observations were made, and it was found 

 that no change whatever occurred during the subsequent three hours— the con- 

 ductivity of the poisoned sensory (afferent) nerves, and the reflex function of 

 the spinal cord being retained, while the conductivity of the poisoned motor 

 nerves was completely suspended. On the two following days, this condition 



