ELKCTKICALLY STIMULATED GANGLION CELLS. 19 



in the two thonvcic ganglia used as control. It was 

 noticed independently by three observers that the 

 nuclei of the cell capsule were shrunken in the stimu- 

 lated ganglion. (See Figs. :J and 4 of plate.) The eighth 

 cervical ganglia, hardened in corrosive sublimate, show 

 the characteristic appearance of the nuclei, with slight 

 difference in the staining of the protoplasm. 



Table VI. 



Cat No. 2. Stimulated 1 hour 4() minutes ; intervals, 

 one minute. 



100 Nuclei. 100 Cells. 



Mean Dliimetors Shrinkage In Mean Diameters 



r Resting 14.91 25.6^ 



Ganglia of ist I Stimulated . . 13.51 

 thoracic. "S 

 Osmic acid. 1 



Examination of the sections shows changes similar 

 to those described for cat No. 1, but less in degree. 



Though no attempt was made to render the stimu- 

 lation equal for cats No. 1 and 2, it is hinted by the 

 results of the two experiments that some sort of a 

 quantitative relation exists between amount of stimu- 

 lation and amount of change in the cells. Such a 

 relation should obtain if we are dealing with cause 

 and effect. To test this point with theoretical pre- 

 cision is, of course, impossible, for we must know, in 

 order to do this, not only the strength of stimulus 

 used, but also that the same h.mount of stimulation 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. In the following 

 series, therefore, we assume that the irritability 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 render these factors as 



