the first to throw all tli()Hj;htof the work asfomplotely 

 as possible off my mind, to think about somctliintr else, 

 to have a story in which I was interested read aloud, 

 or something of the kind to divert my attention. In 

 general also all the measurements were made before 

 the results were footed up, so that the way they were 

 tending could have no unconscious influence upon the 

 measurements. 



The objection has been raised that the changes above 

 described, especially shrinkage of the nucleus, may be 

 pathological. It is true they resemble changes hitherto 

 described as pathological ; but up to the present no 

 attempt has been made to distinguish changes due to 

 fatigue from those caused by disease, and on a priori 

 grounds we should expect the former to precede and 

 shade into the latter. The fact that the change 

 becomes steadily greater as the stimulation is pro- 

 longed, would further indicate that it is due to active 

 processes of the living cell. It would be interesting 

 to know whether stimulated cells will return to the 

 normal condition if given a sufficiently long period of 

 rest. But whether they do this, or whether they die 

 and give place to new cells, is a point for future 

 investigation, and not the question in hand. In either 

 case we are safe in assuming that the changes are such 

 as occur in the normal working of the ganglion cell. 



Conclusion. 



A method has been attained by which changes due 

 to functional activity can be as easily and certainly 

 demonstrated in a ganglion as in a gland. The chief 

 of these changes for the spinal ganglion cells of the 

 frog and cat are : 



As a result of electrical stinuilation : 



-1. Kor the nucleus: 1. Marked decrease in size. 



