ACTION ON REFLEX EXCITABILITY. 



523 



Action on Sensory I^erves. 



Effect on Eeflex Excitahility. 



Experiment LII. —March 22. 



The cerebrum of a living frog of medium size was destroyed. 

 The circulation through the left leg was cut off by ligaturing 

 the arterial trunks above the knee (t;z6?c fig. 162). The sciatic 

 nerve was left uninjured. -J c.c. of the alcoholic extract was 

 then injected beneath the skin of the back. 



Fig. 162. The shading indicates the part to the body to which the poison was 

 carried by the blood. The unshaded part was protected by the ligature 

 from the action of the poison. 



The reflex excitability was then tested at intervals of 5 

 minutes by irritating points above and below the ligature, l^o 

 difference in the sensibility could be detected. 



As the frog was very little affected by the injection, another 

 I c.c. was injected. 



The frog became insensible to reflex irritation in 25 minutes ; 



