480 M. J. GREENMAN 



remaining specimens fell into three different age groups and presented 

 data upon the following points: 



A. Number of fibers in left or control nerve. 



B. Number of fibers in proximal end of operated nerve. 



C. Number of fibers in distal end of operated nerve. 



D. Effect of operation upon body weight. 



Series 3. Three adult unoperated animals, nos. 222, 223 and 224 

 of known weights were used to determine the following points : 



A. The number of fibers in the peroneal nerve of a normal animal. 



B. The difference in the number of fibers at the two ends of that 

 portion of the peroneal nerve used in these experiments. 



C. The sectional area of peroneal nerve fibers of a normal animal 

 and the area relation of axis to sheath. 



Series 4- This series included operated animals nos. 192, 193, 210, 

 211 and 220. Two were adults and three were young animals of known 

 ages; all were of known weights. They furnished data upon the pro- 

 gressive change in the number of fibers in operated nerves. 



Series 5. This series included animals nos. 167, 168, 169, 170, 171 

 and 172. The ages and weights were known. 



This series was used to determine when degeneration is complete. 



Series 6. Animals nos. 316 and 317, Norway rats, of known weights, 

 were used to demonstrate the equality in the number of fibers in the 

 peroneal nerve of each side. 



Series 7. Operated animals nos. 106, 114 and 154. This series was 

 used to furnish data on the sectional area of fibers and the area rela- 

 tion of axis to sheath. These animals were selected from Series no. 2. 



The nerve in the right leg was consistently selected for experi- 

 ment and the corresponding nerve of the left leg was used as 

 the control. 



The observations made in the course of these experiments 

 comprise the determination of the number of fibers and the 

 area relations of axis to sheath in the left or control nerve and 

 similar determinations at different levels above and below the 

 point of operation on the right nerve. 



The nerve selected for operation was the peroneal. This nerve 

 is the anterior (or lateral) division of the sciatic and passes dis- 

 tad beneath the biceps femoris muscle in close contact with 

 the gastrocnemius; it curves over the lateral margin of the gas- 

 trocnemius sometimes piercing the edge of this muscle to dip 

 into the fleshy mass formed by the fused bodies of the upper 

 extremities of the peroneal muscles (P. longus, P. brevis, P. 

 tertius and P. quartus). 



