578 A TEXTBOOK OF PHYSIOLOGY 



Under suitable conditions, the nerve-fibre may become regenerated, 

 with the formation of a new axon, medullary sheath, and neurilemma^ 

 (Fig. 318). There is considerable difference of opinion as to what exactly 

 are the suitable conditions, and also as to what is the exact part played 

 by the spindle cells in this regeneration. It is held by some authorities 

 that " peripheral regeneration " or " autogenetic regeneration " may 

 take place that is to say, that full regeneration of the peripheral 

 part may occur without any connection being made with its original 

 nerve cell or some other nerve cell. Such a view cannot be accepted, 

 for it has been shown that in all experiments favouring this view 

 the possibility of the central influence of a nerve cell has by no means 

 been excluded. When precautions are taken as, for example, 

 enclosing the nerve in a sterilized rubber cap. or transplanting to 

 regions, such as the peritoneal surface of the stomach, where no 

 invasion of nerve-fibres occurs then no regeneration takes place. 

 The central influence of a nerve cell is necessary for the true regenera- 

 tion of nerve. If no central connection is made, the regenerative 

 changes will not pass beyond the stage of the formation of spindle 

 cells. The question then arises as to what is the function of these 

 spindle cells. According to the view of central regeneration, they 

 serve merely as a scaffolding down which the new axon grows from 

 the central end of the nerve. According to another view, the spindle 

 cells, under the influence of the central nerve cell, develop into the 

 new peripheral nerve-fibre, some spindle cells developing into axon, 

 some into medullary sheath, and some into the new neurilemma. 

 The former view is generally accepted. 







