iv GENEEAL PHYSIOLOGY OF NEEVOUS SYSTEM 213 



(d) Among the alkaloids, aconitine and veratrine in 1 per 

 cent solutions rapidly abolish the current of action ; curarine, 



COo 



FIG. 138. Photograph. (Waller.) To show primary excitation of the nerve by a small amount of 

 CO-2 applied between the two white lines. 



digitaline, and morphine diminish its activity ; strychnine in- 

 creases it ; atropine and aconitine are inert. 



() Protracted tetanisation increases the current of action, i.e. 



C0 2 



FIG. 139. Photograph. (Waller.) Shows that a large amount of CO 2 , acting on the nerve 

 during the light band, at first suspends the electrical reactions of the nerve and then has a 

 secondary exciting action. 



has an effect similar to that of C0 2 in small doses (Fig. 140). 

 From this fact Waller argues that tetanisation of nerve is 

 accompanied by a development of CO 2 . 



