EFFECT OF ACTIVITY OX XERVE CELLS 343 



proved technic in fixation and .staining, and by varying the kind 

 of degree of activity in a long series of experiments, using differ- 

 ent animals and studying various kinds of nerve cells, that some 

 degree of uniformity of results might be obtained. 



METHODS 



A resting control animal was used in each experiment. The 

 animals were killed in most cases by bleeding after ether anaes- 

 thesia, the nerve material removed as quickly as possible, cut 

 into small pieces, and the control and fatigue specimens placed 

 in the same fixing solution, imbedded side by side in the same 

 block of paraffinc, cut with the same stroke of the knife, mounted 

 and stained together on the same slide. The detailed data of 

 experiments showing animals used, kind of stimulation, length 

 of time, microscopic technic, etc., are sho\\ii in table 1. In all, 

 fifteen experiments were performed. Examination of the table 

 reveals the fact that almost every foi-mof activity was used; 

 normal activity, forced activity, activ-ity resulting from electrical 

 stimulation, both faradic and galvanic, chemical stimulation, and 

 shock being ai)plied in tlie exi)criments. The kinds of animals 

 used were dogs, cats, rats, sparrows, jjigeons, and frogs. The 

 microscopic technic used was varied considerably, not only as to 

 fixative but also as to staining fluid. The stain most frequently 

 used was Held's modification of Nissl's method. 



The examination of the nxaterial for comparison was facili- 

 tated by having both control and fatigue specimens mounted on 

 the same slide. Changes such as have been previously described 

 as resulting from fatigue were carefully examined for; namely, 

 comparative amounts and distribution of chromatic substance, 

 size of granules, nucleus-plasma relation, relative size of cells 

 and nuclei, etc. In order to determine whether any change in 

 the size of the cell had resulted from activity, a large series of 

 camera lucida drawings were made. These drawings were made 

 of cells without selection. A field was taken, and every cell 

 showing a nucleolus was included. This precaution was neces- 

 sary in order to be assured that the cell was cut through a com- 



