1912.] Contributions to the Histo- Chemistry of Nerve. 127 



the myelin sheath, however, is not dependent upon life, since it occurs in 

 nerves removed from the body and kept under certain conditions, in which 

 the nuclei show no signs of proliferation. 



It follows also that the changes in the myelin sheath are not dependent 

 upon the proliferation of the neurilemmal nuclei, as has been held by some 

 authors. 



The fact that the fragmentation of the myelin sheaths in nerves kept in 

 vitro is not markedly inhibited by cold indicates that the changes in the 

 myelin sheaths are not essentially due to processes of a fermentative or 

 autolytic nature. 



On the other hand contact with an aqueous solution appears to be of 

 essential importance in bringing about the fragmentation of the myelin sheaths 

 in nerves kept in vitro. A process of imbibition appears, therefore, to be a 

 contribiitory factor in bringing about the changes in the myelin sheath 

 characteristic of Wallerian degeneration. 



LITERATURE. 



1. Ranvier, ' Leqons sur 1'Histologie du Systeme Nerveux,' Paris, 1878, vol. 1, p. 289 ; 



vol. 2, p. 69. 



2. Strobe, ' Ziegler's Beitrage z. pathol. Anat.,' 1893, vol. 13, p. 160. 



3. Monckeberg u. Bethe, ' Archiv f. mikroskop. Anat.,' 1899, vol. 54, p. 135. 



4. Merzbacher, ' Pfliiger's Archiv,' 1903, vol. 100, p. 568. 



5. Maccabruni, 'Folia Neuro-Biologica,' 1911, vol. 5, p. 598. 



6. Van Gehuchten, ' Le Nevraxe,' 1905, vol. 7, p. 203. 



DESCRIPTION OF PLATE 4. 



Fig. 1. Cat's nerve kept in Ringer's solution at 37 3 for six days. Osmic acid. Teased 



preparation, x 500 diam. 

 Fig. 2. Microphotograpk of cat's nerve degenerated in vivo, five days after having been 



tied in two places. Segment below lower tie. Osmic acid. Cut in paraffin. 



x 200 diam. 



Fig. 3. Same nerve as fig. 2. Segment between ties. 



