XX Journal of Comparative Neurology. 



oretical and to urge that we suspend our judgment until more proof is 

 furnished. He also mentions a point which many of these critics seem 

 wholly to overlook ; viz. , that the question of anastomosis or complete 

 anatomical independence of nerve cells is only one aspect, and that 

 too a relatively unimportant one, of the general doctrine of the neu- 

 rone. The real issue is. Can the cell theory be apphed in the nervous 

 system and is the nerve cell in its entirety (neurocyte or neurone) a 

 unit of value in the simphfication of our morphological, physiological 

 and pathological data? The experience of the last decade leaves no 

 doubt on this point and we have every reason to look forward to a 

 great extension during the decade now opening of the usefulness of 

 this point of view. Certainly this conception is not incompatible, as 

 several recent authors have pointed out, with intercellular anastomoses 

 of the most diverse and extensive sort, such as we recognize in other 

 tissue systems without feeling obliged to throw over the cell theory. 



Professor Van Gehuchten adheres to his original theory of the 

 polarization of the neurone and defends it at some length against recent 

 objections. He admits the experimental proof of Sherrington and 

 others for double conduction in the central nervous system, but be- 

 lieves that this experimental condition is not realized in the normal 

 physiological functioning. 



The facts bearing upon the theory of amoeboid movements of 

 nerve cells are passed in review. The author believes that it has been 

 proven that in certain experimental conditions the filiform appendages 

 or thorns of the dendrites of cortical nerve cells may be shortened 

 (during cellular activity), or even abolished with varicosity of the den- 

 drites (extreme fatigue and certain intoxications). But whether this 

 involves active amoeboidism of the cells as a normal physiological pro- 

 cess, disturbances of their nutrition or some other factor cannot be de- 

 cided in the present state ot our knowledge. As to the significance of 

 the chromatic or tigroid substance in the nerve cells, he regards it as 

 established that it accumulates in the cell during repose and diminishes 

 during activity. Any disturbance of the normal relations of the cell 

 may result in its loss. It therefore represents reserve material, not a 

 substance indispensable to the the nervous elements. 



On some of these debatable questions, and others which might be 

 mentioned, the author's position will be regarded by many neurologists 

 as rather too radical. His statements are, however, usually made with 

 due caution or reserve, and in particular, the evidence for contrary 

 opinions is fully presented. Dogmatism, even in a text-book, on these 

 subjects would be out of place and the author has doubtless chosen 



