186 ANGULAR OR CAUDATE NERVE CELLS. 



formed material, wliicli last is drawn off at two or 

 more points into fine threads,* These divide and sub- 

 divide into still finer ones at a short distance from 

 the cell, and are, in fact, processes of the nerve cell 

 which become nerve " fibres." The processes in- 

 variably take opjDOsite directions soon after they have 

 left the " cell." 



Nerve cells may exhibit important structural pecu- 

 liarities, so that it is even possible to say, in some 

 instances, after examining a single cell, from what 

 central organ it had been taken. 



In vertebrata there are two principal kinds of 

 central nerve cells which are very distinct from one 

 another, and probably differ in function not less than 

 they do in structure. These are, 1, The Angular or 

 Caudate Nerve Cells, and 2, The Oval, Pyriform or 

 Spherical Nerve Cells. 



241. Angular or caudate nerve cells are charac- 

 teristic of the great central nerve organs of verte- 

 brata, the brain and spinal cord, and attain their 

 maximum of development in the highest mammalia 

 and man. In many of the lower vertebrata these 

 cells are remarkably small, while the other class of 

 cells, on the other hand, is of very large size. If we 

 examine the caudate cells in the gray matter of the 

 spinal cord and medulla oblongata of mammalia, we 

 see lines traversing the cells from each of the many 

 fibres connected with them, and passing to every 

 other fibre, (^Proceedings of the Boyal Society, 1864.) 

 I endeavoured to show that these lines, which were 

 rendered evident by the slow action of acetic acid 

 indicated the paths taken by the nerve currents 

 which traversed the cell. Plate III, fig. 2. 



It is an interesting circumstance, and strongly 

 corroborative of the truth of the views just ad- 

 vanced, that at the very time I was making out the 



* It is probable that no nerye cell exists Tvliicli lias only one 

 single Jibre connected with it. 



