702 HUBER. [Vol. XI. 



experiment, the myelin and axis cylinders had been entirely 

 absorbed in the great majority of the fibres. The old sheaths 

 are filled with a continuous band of protoplasm, imbedded in 

 which are found the nuclei, with their long diameter parallel to 

 the longitudinal direction of the fibre (see PI. XXXIV, Fig, 

 Srt). Even at this stage, however, remnants of the medullary 

 sheath are found in some of the fibres ; and, in these, it is 

 sometimes possible to find small fragments of the old axis 

 cylinder (see PI. XXXIV, Fig. 8 d), which take a deep blue 

 color when stained in anilin blue. The longitudinal striation 

 of the protoplasm as described by Bunger, in which he recog- 

 nizes the anlage for the new axis cylinders, was at no time 

 observed. The protoplasm has a homogeneous appearance 

 and stains faintly blue in sections colored in anilin blue and 

 safranin, in case the safranin is again thoroughly washed out 

 of the specimen ; or may have a faint reddish color in prepara- 

 tions overstained in the safranin. By far the most interesting 

 observations to be made on the operated nerve, examined 

 twenty-one days after implantation, are to be found in the 

 longitudinal sections or teased preparations through the junc- 

 tion of the central ulnar and the implanted piece. In this 

 region the process of regeneration is already established. As the 

 regeneration of the peripheral portion of a divided nerve, and 

 especially the regeneration of the axis cylinders, has been a 

 subject on which observations have been largely at variance, I 

 may be allowed to state some of the opinions expressed. We 

 have, in the first place, the views upheld by Schiff, Laveran, 

 and Remak ; that during the degeneration of the peripheral 

 nerve, the axis cylinder is not affected, but retains its structure 

 and forms the axes of the new fibres. That this is not the 

 case has been clearly shown a great number of times. All 

 axis cylinder stains show, that, during degeneration of the 

 nerve fibres, its continuity is broken, and the resulting frag- 

 ments are always absorbed. Neumann and Eichhorst contend 

 that during degeneration of the peripheral end, the medullary 

 sheath and axis cylinder undergo a chemical change of such a 

 nature that, structurally and chemically, it is not possible to 

 differentiate between the two ; " the process of regeneration 



