1 1 o Journal of Comparative Neurology and Psychology. 



atine nerves were obtained. The stain was unusually complete 

 for methylene blue preparations; the trunk and branches of the 

 palatine nerve, the plexus of meduUated fibers, and the branch- 

 es running from this plexus to the sensory organs, were all 

 demonstrated. But, while in methylene blue preparations of 

 normal nerves the myelin sheaths are colorless and the axis 

 cylinders (especially at Ranvier's nodes) are deeply stained 

 (Fig. 3), in these degenerate nerves it is exactly the reverse. 

 The stain is limited entirely to the myelin substance, and the 

 axis cylinders are not demonstrated, a characteristic staining 

 reaction for degenerated nerves. This is the case not only in 

 the larger branches of the palatine nerve but also in single per- 

 ipheral fibers (Figs. 9 and 10). Even without high magnifi- 





Fig. 9 Fig. 10 



Fig. g. A portion of a medullated nerve Irora a frog's palate, the nerves 



of which had been severed :;5 days before the preparation was made; the dark 



granules are the re nains of the myelin sheaths; the axis cylinders of the fibers 



are not demonstrated. X 360. 



Fig. 10. The distal portion of a single medullated fiber from the same 



preparation as Fig. 9; the myelin sheath is broken up into irregular segments 



which are deeply stained. X 700. 



cation it may be seen that the disintegration of the myelin 

 sheaths is complete (Fig. 9). The myelin has broken up into 

 short segments which are deeply stained, the nuclei of the 

 sheath have apparently disappeared and the nodes of Ranvier 

 cannot be recognized. Comparing a single degenerate fiber 

 from one of these preparations (Fig. 10) with a normal medul- 

 lated fiber (Fig. 3) the difference can be seen at a glance. Not 

 a single normal medullated fiber was found in the large nerve 



