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Contributions to the Histo- Chemistry of Nerve : On the Nature of 

 Wallerian Degeneration.* 

 By Henry 0. Feiss and W. Cramer. 



(Communicated by Prof. E. A. Schafer, F.E.S. Eeceived October 22, 1912, — 

 Read January 23, 1913.) 



(From the Physiology Department, University of Edinburgh.) 

 [Plate 4.] 



Part I. — Introductory. 



When the continuity of a medullated nerve fibre is broken the peripheral 

 segment undergoes a series of morphological changes which are grouped 

 together under the term " Wallerian degeneration." These changes affect all 

 the constituent parts of the fibre, namely, the axis-cylinder, the myelin 

 sheath and the sheath of Schwann. In the early stages they consist of 

 fragmentation of the axis-cylinder, breaking-up of the myelin sheath, and 

 multiplication of the nuclei of the sheath of Schwann together with an 

 increase of protoplasm around them. Although these changes have been 

 studied by numerous observers, and although there is a general agreement 

 with regard to their morphological appearances, different interpretations have 

 been put upon them. And it is not difficult to understand why that should 

 be so. 



The process of degeneration is intimately related to the process of 

 regeneration, and the differences which exist in the interpretation of the 

 latter process are reflected to some extent in the interpretations of the 

 phenomena of degeneration. 



The degenerative changes in the axis-cylinder and medullary sheath are 

 explaiined by some authors as being due to the separation of the protoplasm 

 of the nerve fibre from the nerve cell, its nutritive centre, by others as the 

 result of traumatism, while according to Eanvier (1) they are produced by the 

 mechanical effect of the proliferating neurilemmal cells. The proliferation of 

 these cells again has received different explanations. According to Strobe (2), 

 for instance, the neurilemmal cells are connective tissue cells, and their 

 proliferation is of the nature of the connective tissue reaction, which takes 

 place in the process of repair following the lesion of the specific parenchyma 

 of any organ. According to other observers these cells are of nervous origin 



* The expenses of this research were defrayed by a grant from the Moray Fund of the 

 University of Edinburgh. 



VOL, LXXXVI. — B. K 



