254 Journal of Comparative Neurology. 



' activity of the neuroglia ' he built a theory for the most com- 

 plicated psychic activity.' This contraction and relaxation of 

 the neuroglia may occur automatically or ' under the influence 

 of the will ' [!] just as the blood-vessels under Meynert's plan. 

 These two views should be enough warning against taking to 

 the third possible one-sidedness, namely to the idea that move- 

 ments of the nerve-cells alone constitute nervous activity. 



We do well to consider the activity of the whole tissue 

 when we speak of the function. In the meantime it will of 

 course be our duty to analyze carefully the possible share of 

 each tissue-element, in order to be prepared for a final sum- 

 ming up. 



These considerations seemed necessary as an introduction 

 to a sketch of what we know of the life of certain kinds of 

 nerve-cells. They must be borne in mind in the following dis- 

 cussion and especially when we begin to speak of the diseases 

 of the nervous system. The life and pathology of the neu- 

 rones to which we must limit ourselves here, is by no means a 

 complete pathology of the nervous system. 



The General Physiology and Pathology of the Neurone. 



Any one who takes the trouble to examine many nerve- 

 cells belonging to the different mechanisms described, will admit 

 that there are many fairly characteristic forms. The old method 

 of classifying nerve-cells as unipolar, multipolar, etc., has been 

 modified, and more definite details of structure and outline of 

 form have been used for the classification since the methods of 

 Golgi and Nissl have rendered them easily demonstrable. 

 Nissl himself has furnished a plan for the classification of nerve- 

 cells which is somewhat too complicated to be given in full 

 here. I shall prefer to give here a short sketch of certain cells 

 which are of importance for us in the general plan of the ner- 

 vous system, since only few types are sufficiently studied to 



' Cajal, Alguiias conjecturas sobie el mecanismo anatomico de la ideacion, 

 asociacion y atencion, Madrid, 181)5, 



