72 



Journal of Comparative Neurology. 



These conditions of average variation per millimeter in the 

 number of fibers found at different distances from their cells of 

 origin, are illustrated by curves in Chart I. 



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VI 



mil 



Chart I, showing, in the different spinal nerves of one specimen, the re- 

 lations of the percentage values of the average change per millimeter in the 

 number of fibers in the dorsal and ventral roots and in the trunk. The dis- 

 tances in which the changes occur and the numbers from which the percentages 

 are computed are given in Table I. 



The curves of this chart, constructed from the values in 

 Table III, show more readily than does Table I, (i) that the 

 changes in the two roots of a given nerve do not differ very con- 

 siderably from each other ; (2) that in the several nerves there 

 is no regularity in the amount of variation occurring in a given 

 root, the curves for the two roots crossing each other repeat- 

 ^dJy ; (3) that the percentage variation per millimeter in the 



