REGENERATION OF PERIPHERAL NERVES 497 



fibers, and that this disappearance of myeline has taken place 

 from above downward. This point will be dealt with in another 

 study. 



Figure 2 presents in graphic form the increase in the number 

 of fibers of the regenerated nerves of Series no. 4, the data for 

 which is to be found in table 7. Nos. 192 and 193 are, however, 

 not recorded in the figure since in each case no counts were 

 made beyond the lesion. 



As in figure 1, the length of each transverse line indicates the 

 number of fibers and its position, measured by the scale on the 

 left from 0, the point of operation, tells the level at which the 

 count was made. There are no data for the control nerves. 



The solid line, the broken line and the dotted line are used 

 to connect the entries for nos. 220, 210 and 211 respectively. 



Figures 1 and 2 and the tables on which they are based show 

 similar numerical relations within the regenerating nerve so that 

 we may conclude that there is a progressive increase in the 

 number of fibers from a point at least 7 mm. above the point 

 of operation to the level of the lesion, followed by something 

 of a loss in the next few millimeters distal to the lesion. 



SECTIONAL AREAS: AREA RELATION OF AXIS TO SHEATH 



Numerous methods have been used for determining the diameter, 

 sectional areas and number of fibers in nerves. These methods 

 were summarized by Vashkevitch ('89), since which time con- 

 siderable improvement has been made in optical devices for this 

 work. 



The method which appeals to me as the most accurate is to 

 measure a drawing of the projected and highly magnified image 

 by means of the planimeter. A Zeiss 2 mm. apochromatic objec- 

 tive with no. 4 ocular and tube length of 160 mm. was used in 

 connection with a specially constructed camera of such rigidity 

 as to permit the outlining of fibers on very finely ground glass 

 plates mounted in the plate holder end of the camera. An 

 electric arc consuming 25 amperes of current was used as an 

 illuminant. The optical system was protected from heat by a 



