366 Joiinial of Coiii/'aratiz-c Xcnrology a)ici Psychology. 



then, he the cnmlueting elements. When thrnuiih degeneration. [)ro- 

 loniretl pressure, or the aijplieatinn ot distilled water, a nerve fiber is 

 rendered non-eondiietile. staining shows that the fibrillar substanee 

 has disappeared. l"i>on the renio\al of the al)normal conditions or 

 upon the regeneration ot' a fiber, it is found that the return of func- 

 tional activity is aceomj)anie(l by the reapj)earance of the fibrillar sub- 

 .stance. This substance is theretbre connected with nervous transmis- 

 sion. A constant current ot 0.05-0.2 milliamperes acting tor 10 minutes 

 upon a nerve will produce a polarization of the fibrillar substance 

 and render the nerve non-conductile. If at once fixed and stained. 

 that portion of the nerve near the anode will be much lighter, that 

 portion near the kathode much darker than normal. If after polariza- 

 tion the fixation is delayeil until the conductibility of the nerve returns, 

 it will be stained with equal intensitv throughout its course as in the 

 case of normal fibers. The change which takes place during polariza- 

 tion is a chemical one. The fibrillar sut)stance is set free at the anode 

 and accumulates at the kathi'de. 1 )arkly staineil granules rej»resent- 

 ing tree fibrillar substance were observed at the anode among the 

 fil)rillae of the nerve. This chemical change takes [ilaceonly in living 

 and functional nerves and is theretbre e\idently a vital process essen- 

 tial to nervous transmission. According to BetHe the nervous im- 

 pulse is pr(»duced bv a chemico-physical process. A condition of in- 

 creased affinity for the fibrillai- substance jiasses wavelike along the 

 filirillae and the molecules ot fil>rillar substance are drawn toward the 

 point of stimulation. Coinciilent with thi^ chemical change, a nega- 

 tive electric current is produced. Either this c urrent or the progress- 

 ive movement ot the fibrillar substance may be instrumental in trans- 

 mitting the stimulus. Beihe lielieves that the chemical changes are 

 of most importance in producing nervous imimlses : the chani^es which 

 take place are not oxidation ])rocesses, but merely fluctuations in the 

 chemical affinity of the neurofibrillae. 



Chapter 15 discusses the [lec uliar projjerties of the central nerv- 

 ous .system, .such as tonus, and inhibition of reflexes : on the ground of 

 his well known experiment upon the brain of C(//r/>ii/s. the author re- 

 asserts that both tonus and the transmission of reflexes are not depend- 

 ent on the ganglion cells. In chapters r6-i8 a review is gi\en of the 

 various pheuoniena characteristic of nervous reflexes. .\n interesting 

 account of the effects of various poisons on the nerve elements follows 

 (chapter .19). Mo.st poisons afte( t first the elements of the t-entral 

 nervous .«y.stem, because the fibers there are not protected by the thi<'k 

 .sheaths which surround most perii)heral fibers. Narcotics inhibit the 



