THE PHYSIOLOGICAL CHEMISTRY OP THE NEURON. 557 



"which a saline solution of the residue of the alcoholic extract 

 produces." This fall "is abolished," they further state, "if the 

 animal has been atropinized." We may incidentally remark 

 that these few lines embody the pathogenesis of most neuroses 

 attended with degeneration, if our views are sound, since 

 we have here the phenomena incident upon arrest of function, 

 auto-intoxication, and toxic suprarenal insufficiency. But di- 

 rectly bearing upon the subject in point is the evident iden- 

 tity of cholin as a product of degeneration. It "has its source 

 in lecithin decomposition and putrefaction," says Howell. 

 But it is likewise, as we have seen, a waste-product of normal 

 nervous-tissue metabolism, being eliminated with the bile in a 

 modified form. That cerebrin is also a product of putrefaction 

 and of physiological metabolism is suggested by two facts: it 

 is found in pus-corpuscles and its formula and that of cholin 

 present considerable analogy. Even taking as standard that 

 furnished by H. Miiller, which has given rise to considerable 

 controversy, cerebrin is C 17 H 33 N0 3 , while cholin is C 5 H 15 N0 2 . 

 Lecithin, therefore, becomes the functional ground-substance of 

 the cell-body of the neuron, just as it is in the nerve. Both in 

 the neuron and its continuation, the nerve, therefore, the vascular 

 fibrils carry blood-plasma, which, by passing through their walls, 

 maintains a continuous reaction, of which the phosphorus of 

 the lecithin and the oxygen of the blood-plasma are main re- 

 agents and chemical energy the end-result. The relationship 

 between the vascular fibrils and the ground-substance, nucleus, 

 etc., is well shown in the annexed familiar engraving. 



But lecithin, though a useful product of metabolism, re- 

 quires in its formation the aid of protoplasmic function, as 

 does, in the muscle, the elaboration of myosinogen. In the 

 cell-body this is probably performed, we have seen, by structures 

 which the Nissl bodies, as nucleo-albumins, represent. Indeed, 

 in a study of the action of fixatives upon protoplasm Hardy 

 found 47 that, "when a soluble colloid is fixed by the action of 

 a fixing reagent, it acquires a comparatively coarse structure 

 in the process, which differs wholly or in part from the struct- 

 ure of the soluble colloid." Again, that these protoplasmic 



47 Hardy: Journal of Physiology, May 11, 



