THE IDENTITY OP NEUROGLIA. 543 



role in non-medullated nerves. That the myelin is the seat of 

 a combustion process during which heat is liberated and a de- 

 composition product, cholin, is formed, we have seen. If we 

 now consider the composition of the active component of 

 myelin, lecithin, i.e., carbohydrates and phosphorus, and its 

 analogy, as regards carbohydrates, to myosinogen, the prob- 

 ability that it serves as a source of energy, as does the latter 

 when in contact with oxygen, suggests itself. That such is the 

 case, however, is shown by the fact that the contents of the 

 neuraxon or axis-cylinder fulfills the conditions necessary for 

 methylene-blue staining, as laid down by Ehrlich, i.e., oxygen 

 saturation and alkalinity, the characteristics of blood-plasma. 

 Indeed, it seems to us permissible to conclude that: 



1. Myelin, or the white substance of Schwann, is to nerve- 

 structure what myosinogen is to muscle-fiber: i.e., its immanent 

 source of energy. 



2. The axis-cylinder and the canaliculi derived therefrom 

 are made up of fibrils that serve as channels for blood-plasma. 



3. A part of this Nood-plasma penetrates into the axis-cylin- 

 der through Ranvier's nodes. 



4- Lecithin, a body composed mainly of hydrocarbons and 

 phosphorus, the active constituent of myelin and a prominent com- 

 ponent of the electric organ of the ray, when exposed to the action 

 of the oxidizing substance liberates energy: i.e., nervous energy. 



Continuing our quotations from Professor Barker's arti- 

 cle, we will introduce the various points of comparison which 

 appear to us to sustain our interpretation of Apathy's neuro- 

 fibrils. "Inside the ganglion-cells a reticulum of fine fibrils 

 derived from the neuro-fibrils in transit can be stained a beau- 

 tiful deep-violet color by Apathy's chloride-of-gold method." 

 That the latter method can be considered as similar in action 

 to the methylene-blue method and that the stain follows the 

 same channels and affects the same chemical constituents of 

 the plasma is shown by the following remark of Professor 

 Barker's: "With a little care and a good sample of methylene- 

 blue the nerve-endings and the axis-cylinders of medullated 

 fibers, with which they are continuous, can be stained in a 

 way far surpassing in constancy and completeness the best re- 

 sults of the uncertain gold-chloride procedure." As the methy- 



