LitenDy Notices. > xxxiii 



axis cylinder staining method. It seems to me highly probable that 

 these so-called islands or colonies of new axis cylinders, which are said 

 to develop in the more distal end of the proximal segment of a severed 

 nerve, independent of the central axis cylinders, are not such in reality. 

 Observers who adhere to the central theory of regeneration — namely, 

 that the new axis cylinders observed in the degenerated portions of 

 severed nerves in process of regeneration, are outgrowths of the cen- 

 tral axis cylinders — have observed small bundles of newly formed axis 

 cylinders or single .axis cylinders, which usually present a tor- 

 tuous course, especialiy as they approach the region of the wound of 

 the severed nerve. This observation is more explained if we accept 

 Ballance and Stkwart's observations on the formation of what they 

 term the ''primitive end-bulb," which, as they state, is found within 

 the first and second days after section of the nerve, as a result of "the 

 curling up of the loose ends of the divided fibers." The discursions of 

 these small bundles are of such extent that they are cut several times in 

 sections parallel or nearly so to the long axis of the nerve, and in this 

 manner, as it appears to me, are formed the islands or colonies of 

 newly formed axis cylinders, surrounded by delicate medullary sheaths, 

 described by Ballance and Stkwakt. Carefully made serial sections 

 are necessary to reach correct conclusions on this point. The appear- 

 ances presented by their preparations do not warrant the conelusions 

 drawn by them (if 1 may be allowed to interpret their results) ; these 

 preparations certainly admit of a different interpretation than that which 

 they have given them, and may be used quite as readily to substandate 

 the central theory of nerve regeneration. In discussing the results 

 which these observers obtained by means of Cox's modification of the 

 GoLGi method, consideration should be given primarily to the method 

 itself. It is of coarse well known that tissues treated after this method 

 are "stained" by precipitation; cell structures are in no sense differen- 

 tiated and the relation of fibrillar structures to cell protoplasm is often 

 not clearly and definitely brought out. Attention may be drawn to the 

 results obtained with the Golgi method in staining neuroglia tissue; in 

 such preparations, the neuroglia fibers are made to appear as processes 

 of the neuroglia cells. The precariousness of the method is such that 

 it must be regarded as somewhat hazardous to make definite statement 

 concerning the length of processes or fibers and of the continuity of 

 fibers, basing such statement on the appearances presented by Golgi 

 preparations. I can not, therefore, regard the Golgi method, or mod- 

 ifications thereof, as especially applicable in the study of peripheral 

 nerv'es in process of degeneration or regeneration. The figures show- 



