498 



M. J. GREENMAN 



water jacketed condenser through which tap water flowed 

 continuously. 



By this means we were able to focus upon any fiber and obtain 

 a sharp image which was outUned with pencil on the ground 

 glass at a magnification of 4000 diameters. 



Measurements were then taken by the planimeter directly 

 from the glass plate and recorded in square centimeters. Each 

 planimeter measurement was repeated five time to insure accu- 

 racy and the result reduced to square micra. 



SECTIONAL AREAS OF NERVE FIBERS FROM THE PERONEAL NERVE 

 OF NORMAL ANIMALS 



Series no. 3 consisting of three unoperated animals, nos. 222, 

 223 and 224, of known weights was utilized fer these measure- 

 ments. 



To determine the sectional areas of normal nerve fibers, forty 

 of the largest nerve fibers from the proximal end and forty of 

 the largest nerve fibers from the distal end of each specimen 

 were measured. These measurements were then tabulated in the 

 order of their size beginning with the largest fibers. The aver- 

 ages of the first ten records were then taken, the percentage rela- 

 tions of the axis computed and the data arranged as in table 9. 



It will be seen from this table that the average of the ten 

 largest fibers in the proximal end of each nerve gives us a meas- 

 urement of 109.8 square micra for no. 224, 137.7 square micra 

 for no. 223 and 150.3 square micra for no. 222. The average 



TABLE 9 

 Normal rats: Sectional area of fibers; relation of axis to sheath 



Average sectional area of the proximal and distal ends, 113.6 square micra. 



