ELECTKICALLY gTIM0LATED GANGLION CELLS. 7 



very widely in staining and general appearance. The 

 stimulated nerve was not divided, so that the contrac- 

 tions of the muscle supplied by it could be used to 

 indicate the healthy condition of the nerve. If the 

 nerve was conducting impulses peripherally to its 

 muscle, it was taken for granted that it was conduct- 

 ing impulses in like manner centrally to its ganglion. 



In general, as a means of stimulation, the ordinary 

 combination was used, of Du Bois-Reymond coil, plat- 

 inum electrodes, and bichromate or copper sulphate 

 cell : and the strength of stimulus was determined 

 within physiological limits by touching the electrodes 

 to the tongue before beginning to stimulate. Special 

 apparatus to regulate the strength of primary current 

 and number of stimuli per second may best be de- 

 scribed in connection with the purpose of special 

 experiments. Intervals of rest were generally al- 

 lowed. This was at first managed by having a key 

 in the primary circuit and making and breaking the 

 circuit by hand. Later, this part was relegated to 

 clockwork, which spaced the intervals with more pre- 

 cision and removed the chief feature of irksomeness 

 from the operation. 



At the end of the desired length of time the stimu- 

 lated gangbon, with its mate of the opposite side, was 

 as quickly as possible excised and the process of fixing 

 and hardening begun. The method from this point on 

 is directed toward having the two ganglia pass through 

 identical treatment. In no single instance, no matter 

 how many controls tvere used, loere they separated 

 from, the time they left the animal to the time ivhen, 

 placed side by side upon the same slide, they tvere 

 ready for study. Not only were they carried through 

 the same reagents, but, in every case, through the 



