PRODUCED BY ATROPIA IN COLD-BLOODED ANIMALS. 



487 



movements. A slight touch of the skin caused a violent attack of emprostho- 

 tonic tetanus, which lasted for seven seconds, and was succeeded by a series of 

 clonic spasms in the posterior extremities and the abdominal muscles. During 

 the tetanus, the posterior extremities were stiffly extended, with their webs 

 stretched, while the anterior were rigidly incurved. Tetanic convulsions could 

 be excited at any time by repetitions of the excitation, and they sometimes 

 occurred spontaneously. In the intervals between them, the anterior extremi- 

 ties continued rigidly flexed. 



During the third, fourth, and fifth days, the frog remained in this state, 

 except that, on the fifth day, the convulsions were less powerful and prolonged. 



On the sixth, seventh, and eighth days, excitation caused merely sudden spas- 

 modic movements; but the anterior extremities were still rigidly flexed inwards. 



On the ninth and tenth days, the frog was in a normal position ; voluntary 

 movements were freely executed ; but there was still a slight increase in the 

 activity of the reflex function. 



On the twelfth day, the symptoms had completely disappeared. 



This experiment, therefore, proves that combined doses of strychnia and 

 sulphate of methyl-strychnium may produce symptoms that in every detail 

 imitate the most obvious of the effects of atropia on the cerebro-spinal nervous 

 system of frogs. By comparing the diagramatic representation of this experi- 

 ment with that of Experiment XVI. (p. 480), it will be seen how close are the 

 resemblances. 



c 



i 

 i 

 i 



\ 

 \ 



\P> 















D 





i 

 i 

 i 

 i 

 i 

 i 





\ 





Si 





S9 











\ 



SI 



<qFi_ 



— ■ 



P3 



/>* i^~ £1_ 





A 







i 





h 



t 



3 f 



i* is t6 t'-r t'n 



is 



in 



B 



Diagram 6* 



It is therefore possible, by combining a paralysing with a convulsant sub- 

 stance, to produce in frogs paralytic and tetanic effects, which in their relative 

 and general characters are undistinguishable from the paralytic and tetanic effects 

 of atropia. 



The next step was to administer these substances simultaneously to a 

 mammal. 



It has been shown in a paper communicated to this Society by Dr A. Crum 



* AB, line of normality, each division of which, ot v t^t 2 ,t 2 t % , &c, represents a period of 

 twenty-four hours ; CD, line of complete paralysis ; oj>- 1 p 2 p z , &c, curve of paralysis ; os 1 s 2 s 3 , &c, curve 

 of spinal-stimulation ; t^p v t 2 p 2 , &c, ordinates whose length roughly represents the amount of the 

 paralytic action ; t 1 s l ,t 2 s 2 , &c, ordinates whose length roughly represents the amount of the spinal- 

 stimulant action. 



