No. 2.] 



CHANGES IN NERVE CELLS. 



127 



sible, half-grown kittens were used throughout. The strength 

 of stimuH was regulated by placing a rheocord, resistance-box, 

 and galvanometer in the primary circuit derived from two i 1. 

 copper sulphate cells. By manipulation of the resistance-box 

 and rheocord, the galvanometer needle was brought to a given 

 position and held at this point during the whole of each experi- 

 ment. The experiments were made in rapid succession and 

 without altering the setting of the apparatus. Stimuli were 

 purposely not severe, because of the long duration of some of 

 the experiments. But not until the series had been studied 

 was it clear that the stimulation was too slight for the most 

 definite results. 



Two experiments were made to test the effect of stronger 

 stimulation and the influence of the rest interval, with the 

 suggestive result expressed by Table VIII. 



1 The minus sign indicates that the nuclei of the right side are slightly larger in 

 this case. In the only other set measured from a normal pair, the nuclei were also 

 a little larger on the right side. 



- Sets marked " T." are measured by a third person, with whom every precaution 

 was taken to obtain purely mechanical and unprejudiced measurements. 



' Sets marked " S." (selected) are those in which only nuclei in cells of over 50 ju 

 diameter were measured. The shrinkage volume per cent is given for the two 

 unselected sets, not marked " S.," and are thus comparable with other members of 

 the series. The shrinkage of the selected sets is 49.9 %. 



