718 DRS CRUM BROWN AND FRASER ON THE CONNECTION BETWEEN 



it was impossible to excite any reflex movement, although strong irritations were 

 applied to the skin of both the poisoned and non-poisoned regions, and to the left 

 sciatic nerve. At this time, the contractility of the muscles was unimpaired, the 

 conductivity of the right (non-poisoned) sciatic nerve was retained, and the 

 contractions of the heart were at the rate of twenty in the minute. 



It is obvious that, in this experiment, the motor nerves were completely 

 paralysed before the reflex function of the spinal cord was suspended. 



Experiment LXXVIII. — After ligaturing the blood-vessels in the right thigh 

 of a frog, weighing 110 grains, we injected a solution containing three-tenths of a 

 grain of hydrochlorate of Mr Morson's conia, under the skin at the left flank. 

 In forty-nine minutes, no reflex movements could be produced by irritation of 

 the skin, whether of the poisoned or non-poisoned regions. The left sciatic nerve 

 was now exposed ; and, on galvanising its trunk, it was found that feeble 

 twitches occurred in the toes of the left (poisoned) posterior extremity, while no 

 reflex movements occurred in the right (non-poisoned) posterior extremity, or in 

 any part. It was ascertained, at the same time, that the muscles everywhere 

 contracted freely when directly stimulated, that the right sciatic nerve retained 

 its functional activity, and that the heart's beats were occurring at the rate of 

 eighteen in the minute. The condition of retained, though impaired, conductivity 

 of the poisoned motor nerves, of retained conductivity of the non-poisoned (right) 

 sciatic nerve, of apparently unimpaired contractility of the muscles, coexisting 

 with complete suspension of the reflex function of the spinal cord, continued 

 until one hour and ten minutes after the administration of the poison. At one 

 hour and fourteen minutes, however, the left (poisoned) sciatic nerve was found 

 to be completely paralysed. 



We learn from this experiment that Mr Morson's conia may so energetically 

 affect the spinal cord, as to suspend its reflex function, before the motor nerves 

 are completely paralysed. The motor nerves, certainly, were affected at an early 

 stage, and, even before the suspension of the reflex function of the spinal cord, 

 their conductivity was so far impaired, that merely very feeble twitches could be 

 excited by galvanising them. The general paralysis that was present in the 

 poisoned region was, no doubt, to a considerable extent due to their impaired 

 activity. Still, the action of this substance on the reflex function of the spinal 

 cord was, at least, as important a cause of paralysis as the action on the motor 

 nerves. In Experiment LXXL, likewise, both actions co-operated in the produc- 

 tion of the paralysis, but the motor nerves were paralysed in it before the reflex 

 function of the spinal cord was completely suspended. 



These two experiments represent two varieties of action, which we have 

 observed in our experiments with Mr Morson's conia. In both, the motor nerves 

 and the spinal cord were markedly affected ; but in the one, complete loss of 

 function occurred in the motor nerves before it occurred in the spinal cord, and 



