No. 3.] PERIPHERAL NERVES. 703 



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consists in a differentiation of this common substance into 

 a new axis cylinder and a new myelin" (see Howell and 

 Huber, from whom this quotation is taken). Neumann 

 believes that the new axis cylinder is developed in short 

 pieces, one for each internodal segment. This segmental 

 anlage is, according to Neumann, seen in the peripheral end 

 of the central portion of the injured nerve, in the wound (in 

 his experiment, the continuity of the axis cylinders and myelin 

 was interrupted by means of a ligature tied very firmly around 

 the nerve and then removed), and in the central end of the 

 peripheral stump, extending from here to the periphery. 

 Biinger states that the new axis cylinders are developed from 

 the proliferated protoplasm and nuclei of the degenerating 

 fibre. By the end of the second week after the injury, the 

 protoplasm becomes longitudinally striated, and is differen- 

 tiated into a band-like structure, the new axis cylinder. The 

 development takes place in short segments, which later unite 

 to form the band, Stroebe and Notthaft, in two very careful 

 researches, have critically reviewed Bunger's results, and find 

 no evidence in support of his statements. Among those who 

 believe that the new axis cylinder is developed from some one 

 of the cellular elements in the peripheral portion of the injured 

 nerve, may be mentioned Hjelt and Wolberg, who trace its 

 origin from the cells of the connective tissue surrounding the 

 nerve fibres ; and Einsiedel, Korybutt-Daskiewics, Beneke, and 

 Leegard, who maintain that the proliferated nuclei of the 

 sheath of Schwann are the anlage for the new axis cylinders. 

 The present conception of the structure and development of 

 the axis cylinder, according to which it is regarded as a long 

 process extending uninterruptedly from the nerve cells to its 

 place of distribution, either in a motor or sensory ending, 

 makes it difficult to accept any one of the above views. In 

 support of this assertion, we may finally give the observation 

 of a goodly number of investigators, who maintain that the 

 new axis cylinder is formed during regeneration after the man- 

 ner of its development in the embryo, that is, in the form of a 

 bud or a sprout, which grows from the ganglion cell (or its 

 severed process, the axis cylinder), toward the periphery. 



