No. 3-] PERIPHERAL NERVES. 709 



Fig. 13, in which is reproduced a part of a longitudinal section 

 through this region from a nerve removed 1 1 7 days after 

 implantation. Some of the small bundles, it will be seen, have 

 a definite direction, parallel to the long axis of the nerve ; 

 others have a wavy or twisted course {c-c), and one small 

 bundle, d, is seen in cross-section. A study of many sections 

 from this region gives me the conviction that the new nerve 

 fibres are winding their way through the spaces in the connec- 

 tive tissue. 



In the implanted portion the fibres are arranged in bundles, 

 separated by fibrous connective tissue, which varies in amount 

 in different parts of the implanted nerve. As seen in cross- 

 section, the bundles show a closer proximity in the axial part 

 than they do toward the borders. Here one meets with small 

 bundles, separated entirely from the other nerve fibres, and 

 some distance from them. Each small bundle is surrounded 

 by a distinct layer of connective tissue forming a perineural 

 sheath. The distance separating the bundles is much greater 

 in the peripheral part of the implanted nerve than nearer the 

 central wound, and the bundles are not so numerous. (See 

 PI. XXXV, Figs. 17 and 18.) The former shows a portion of 

 a cross-section of the central, the latter of the peripheral end 

 of an implanted segment 157 days after operation. In longi- 

 tudinal sections of the implanted piece a large number of the 

 nerve fibres have a direction parallel to the axis of the nerve, 

 but are often slightly wavy ; some of the small bundles, 

 especially such as occupy a position near the borders of the 

 implanted nerve, pass out of it, and are lost in the surrounding 

 connective tissue. 



Very interesting observations are to be made on longitudinal 

 sections of the peripheral wound in the nerves of the experi- 

 ments above referred to (about 120 days after implantation). 

 PI. XXXV, Fig. 14, presents an appearance commonly met 

 with. The course of the axis cylinders is here very much more 

 irregular than in any other part of the regenerated nerve. 

 The new axes are often seen deflected to one side or the other, 

 and it is not unusual to see them turned back, and growing 

 toward the center for a short distance. In sections, owing to 



