PRODUCED BY ATEOPIA IN COLD-BLOODED ANIMALS. 



483 



paralysis is so rapidly and completely produced that no spinal-stimulant symptom 

 can be exhibited. Death results either from an extreme degree of the paralytic 

 action, or, possibly, from some other effect of atropia. In neither case, however, 

 does the paralytic action diminish sufficiently (if it diminish at all) to permit any 

 effects of spinal- stimulation to appear, for death occurs during a high intensity 

 of the paralytic action. Diagram 3 represents an experiment (XLII. of Table I.) 

 in which a large fatal dose of sulphate of atropia was administered to a frog. 

 The reflex activity was destroyed in a few minutes, and the conductivity of the 

 motor nerves was completely suspended in one hour and forty minutes. Death 

 occurred during the complete paralysis. 



pzb- 



t're t'20 tu- 



Diagram 3.* 



As the curve of paralysis, op 4 p 8t &c., rises rapidly to the line of complete 

 paralysis, CD, and crossing, terminates above it (at the time of the occurrence of 

 death), while the curve of spinal-stimulation, os 4 s & , &c, rises with comparative 

 slowness, it is obvious that no spinal-stimulant effect can possibly be manifested. 

 In frogs, the only symptoms of a fatal dose of atropia are, accordingly, those of 

 paralysis, notwithstanding that such a dose exerts a large amount of spinal-stimu- 

 lant action, which is represented in the diagram by the curve os 4 s 8 s 12 , &c. 



In mammals, fatal doses of atropia invariably produce spasms and convulsions. 

 We at once see why this should be so, if we bear in mind that mammals are less 

 susceptible than frogs to a paralytic action. I have delineated in Diagram 4 the 

 symptoms that were observed in an experiment (Experiment LX.) in which a 

 solution, containing fifteen grains of sulphate of atropia, was injected under the 

 skin of a dog, weighing nine pounds. Partial, but distinct, paralysis was first 

 observed in eleven minutes, and spasms, with increased reflex excitability, in 

 sixteen minutes. They both gradually increased in severity — the paralytic action 

 causing inability to stand in twenty-two minutes, and the spinal-stimulant pro- 

 ducing the first of a series of frequently recurring tetanic convulsions in nineteen 

 minutes ; and death took place one hour and eighteen minutes after the adminis- 

 tration. 



* AB, line of normality, each division of which, ot v tjt^, t % t l2 , &c, represents a period of forty 

 minutes; CD, line of complete paralysis; op*p 8 p l2 , &c, curve of paralysis ; os 4 s 8 s 12 , &c, curve of 

 spinal-stimulation (tetanus, &c.) 



