126 HODGE. [Vol. VII. 



nuclei of the cell capsule were shrunken in the stimulated gan- 

 glion. This may be seen by comparison of Figs. 2, 4, and 5 

 with Figs. I and 3 of PI. VII, and holds good also for diurnal 

 fatigue, for which compare the capsular nuclei of Figs. 7 and 6, 

 PI. VIII. This may indicate the supposed nutritive function of 

 the capsular cells. 



The 8th cervical ganglia, hardened in corrosive sublimate, 

 show for the right ganglion the shrunken and darkly stained 

 nuclei characteristic of stimulation (compare nuclei in Figs. 3 

 and 4, PI. VII). The vacuolation of the protoplasm is not brought 

 out, although well preserved by the same method in some of 

 the frog's ganglia. Flemming's fluid and picric acid happened 

 to be used here by way of experiment, but were found to give, 

 on the whole, inferior results. 



TABLE VI. 



Cat No. 2. Stimulated one hour forty minutes ; intervals 

 one minutes. 



Diff. 1.40 



Examination of sections shows similar changes to those 

 described for cat No. i, but much less in degree. 



No attempt was made to render the stimulation equal in the 

 two experiments ; but it is strongly hinted by the results that 

 a quantitative relation exists between the amount of stimula- 

 tion and amount of change in the cells. Such a relation should 

 obtain, if we are dealing with physiological cause and effect. To 

 test the point with mathematical precision is, of course, impossi- 

 ble ; for we must know, in order to do this, not only the strength 

 of stimulus used, but also that the same amount of stimulus is 

 distributed to the same number of cells ; and, further, that the 

 ganglion cells of one animal are exactly as irritable as those of 

 another animal. However, to decide the matter, a series of 

 experiments was arranged under the assumption that the irrita- 

 bility of cats is in general the same, and that the same nerves 

 in different cats connect approximately with the same number 

 of ganglion cells. To make these factors as nearly alike as pos- 



