68 'Journal of Comparative Neurology and Psychology. 



the effect of the current upon the nerve cells. To avoid the pos- 

 sibility of this criticism another experiment was devised. 



A number of well fed snails which had been living upon damp 

 earth were taken. A part of these were killed at once and the 

 rest were fatigued by poking them with a sharp needle until they 

 would no longer withdraw from the point of stimulation. This 

 process was somewhat slower than the fatigue by means of the 

 electric needle and took from two and a half to three hours. A 

 comparative study of the two sets of animals revealed conditions 

 entirely in harmony with the previous experiment. The nerve 

 cells of the rested animals show the presence of the vacuoles with 

 the bodies in them, the nerve cells of the fatigued animals show 

 the presence of the vacuoles but the solid bodies have disappeared. 

 Evidently there has been some change in the cells of the animal 

 due to the excessive amount of work which the animal was called 

 upon to do. 



Up to this time in our work no attempt had been made to ascer- 

 tain whether it were possible to see these structures in the hving 

 nerve cell. It was our good fortune to find that with care in manipu- 

 lation and careful observation it was possible clearly to distin- 

 guish these several structures in the living, nerve cell. A trace 

 of methylene blue added to the salt solution in which the cells 

 were examined brought out the bodies with great distinctness with- 

 in a few seconds and they could be easily studied. 



The next step in our work was to study the disappearance of the 

 bodies in the nerve cell under the microscope — to watch the 

 process. The results were even better than we had hoped. Small 

 electrodes of platinum foil w^ere attached to a slide and the nerve 

 cells mounted between these electrodes. The electrodes were 

 connected with the secondary coil of an inductorium. Under the 

 tV inch oil immersion lens the bodies in the vacuoles showed with 

 great clearness and sharpness of outline. When the current was 

 first applied there was no change in the appearance of the bodies 

 but within a few minutes a change appeared. The outline of the 

 body lost its sharpness. The body seemed to grow larger in size. 

 The line of demarcation between the solid body and the liquid 

 became less and less distinct and finally disappeared. The sub- 

 stance of the body appeared to be going into solution in the liquid 

 of the vacuole. At the same time, there was a slight change in 

 color, the body taking on the color of the liquid. This process 



