THE IDENTITY OF NEUROGLIA. 



541 



injection of a solution of methylene-blue dissolved in salt solu- 

 tion intra vitam into the blood-vessels of an animal, the axis- 

 cylinders of many of the nerve-fibers (see Fig. 1), as well as 

 numerous (particularly sensory) nerve-endings (see Fig. 2), 



Pia. 1. NERVE-FIBERS FROM A FROG INJECTED WITH METHYLENH- 

 BLUE (METHOD OF EHRLICH). (After Kolliker.) 



The axis-cylinders are stained dark blue. In places the myelin 

 sheath is somewhat stained. The nodes of Ranvier and the divisions of 

 the fibers at some of the nodes are well shown. 



were stained after a time, when exposed to the air, an intense- 

 blue color, the other tissue-elements remaining little or not at 

 all affected/' It seems clear that, if a solution introduced 

 through blood-vessels can stain the axis-cylinders, the liquid 



