CoRiAT, Chemistry of the Nervous System. i 5 5 



lecithin on white rats, to show its effect upon their growth, coucludes 

 as follows : White rats which receive! the lecithin either by injection 

 or feeding, gained in body weight more rapidly than those which did 

 not receive it, the gain in the experimented rats being on the average 

 ■60 % greater than in the controls. The relative weight of the central 

 nervous system in the lecithin rats was normal and contained the same 

 proportion of water and solids as in the controls, this being another 

 indication of the normal character of the growth The peripheral 

 nerves in both groups also grew normally, as shown by the relative 

 area of the axis cylinder to its sheath. The action of the lecithin ap- 

 peared to be that of a stimulating agent for normal growth, and the 

 rats which received it showed a greater power of resistance to unfav- 

 orable changes in their surroundings. 



Koch's work on the action of electrolytes on colloidal solutions of 

 kephalin and lecithin is also of interest, as showing the possibilities of 

 the study of metallic poisons on the various constituents of the central 

 nervous system, from the standpoint of physical chemistry. These 

 colloidal solutions, which form perhaps the nearest artificial approach 

 to the substratum of the living cell, are precipitated l)y divalent 

 katious, while precipitation is prevented by univalent and trivalent ones. 



The most important constituent of the individual cell is the Nissl 

 bodies, which consist principally of nucleic acid. This acid is not 

 found pure, but in combination with proteids forming nucleo-proteids 

 which are probably the most complex bodies in a living organism. 

 These compounds have the property of acids, contain phosphorus and 

 iron and also the purin and pyrimidin bases. There is also a carbo- 

 hydrate, the exact nature of which is unknown, but which gives the 

 furfurol reaction and probably belongs to the pentose group. The pur- 

 in bases of cerebronucleo-proteid are adenin and guanin, and the py- 

 rimidin bases, according to Levene, thymin and cytosin. The amount 

 of phosphorus is lower than in the nucleo-proteids from other tissues. 

 Under pathological conditions, especially in general paralysis, this nu- 

 cleo-proteid passes into the cei-ebro-spinal fluid ; the proteid in the nor- 

 mal fluid consists almost entirely of serum-globulin, nucleo-proteid be- 

 ing completely absent. 



During the last few years the cerebro-spinal fluid has called forth an 

 immense literature, partly because it may contain the products of nerve 

 degeneration (cholin, glycerophosphoric and lactic acids, lecithin ?), 

 and partly because in conditions of acute or chronic inflammatory pro- 

 cesses in the brain, certain cells may appear in the fluid, the finding 

 of which is a valuable diagnostic aid. The chromo- and cyto-diagno- 



