CHAPTER VII. 



NERVE-TISSUE. 



THE primary structural element in nerve-tissue is 

 the nerve-cell. Nerve-cells have the most diverse 

 forms, and always possess one or more branching or 

 unbranched processes. In certain cells the un- 

 branched processes are extremely long, become as- 

 sociated with other tissue elements, and constitute 

 the nerve-fibres. Both nerve-cells and their processes, 

 nerve-fibres, are enclosed and supported by pecu- 

 liarly arranged connective tissue, and supplied with 

 blood and lymphatic vessels. The nerve-fibres form, 

 for the most part, the white matter of the nerve- 

 centres and the peripheral nerves, while the cells 

 enter largely into the composition of the gray matter. 



In studying nerve-tissues, we have then to consider: 



1. Nerve-fibres, and the supporting connective- 

 tissue structures, with their accessories. 



2. Nerve-cells. 



I. NERVE-FIBRES, ETC. 



These are of two kinds : a, medullated, and b, 

 non-mediillated. This distinction corresponds with 

 the physiological and anatomical classification of 



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