LECT. XII. XIII. GAXGLIONIC NERVES. 247 



they are becoming weaker, we then perceive that when 

 the latter has acted upon the heart for some time, the 

 movements become more frequent, and the augmented 

 frequency continues for several seconds after the current 

 has been interrupted. 



The same effects take place with the vermicular move- 

 ment of the intestines when these organs are subjected to 

 the influence of the current. 



If we reflect on the importance which the ganglionic 

 system possesses in the performance of the organic func- 

 tions of animals, we can easily understand how very insuf- 

 ficient are the researches hitherto made on this subject. 



The difference of action exercised by the current upon 

 the nerves of the life of relation, and on those of organic life, 

 is very marked. In the former, its effects are manifested 

 only in the first and the last moments of its application ; 

 in the latter, on the contrary, they are slow to appear, 

 continue during the passage of the current, and even per- 

 sist after it has been interrupted. 



Effects of the Interrupted Current. Having now exa- 

 mined the influence exercised upon the irritability of nerves 

 by the passage of the continued current, it remains for us 

 to examine the effects produced by the current interrupted 

 and re-established at short intervals, in such a way that its 

 action is very frequently repeated upon the nerve. 



For this purpose I fix to the table, by means of small nails, 

 a frog prepared in the usual manner. I connect one of 

 the conductors of the pile with one of the nails, and with the 

 other conductor I touch, many times successively, another 

 nail, thus establishing and interrupting 'successively, the 

 circuit, in a very short time. We see the frog violently 

 extending its limbs, as if affected with tetanic convulsions, 

 whether the current which thus traverses it by jerks be 

 either direct or inverse. 



