190 BIOPLASM OF THE NERVE CELL. 



coTirse of the fibres wliich result from the division and 

 sub-division of the processes of the caudate nerve 

 cells, according to my view, will be understood if 

 fig. 1, Plate III, page 187, be referred to. All the 

 fibres of every cell divide and subdivide into finer 

 fibres which are continued to peripheral parts. 



It is probable that the caudate nerve cells are not 

 sources of nerve force. These cells are fewer in 

 number and comparatively insignificant in the lower 

 vertebrata, particularly batrachia and fishes. In the 

 invertebrata they do not exist at all, and it is doubt- 

 ful if any "cells" precisely corresponding to them 

 are to be found in their stead. 



242. Biotilasiii of the nerve cell. — The bioplasm 

 of the nerve cell is embedded in the material which 

 exhibits the lines crossing in all directions, and no 

 doubt this substance is formed from it ; but, as far as 

 I have been able to ascertain, no nerve fibre arises 

 from, or is connected with, the bioplast (nucleus or 

 nucleolus). It appears probable that the caudate 

 cells are the stations at which nerve fibres pursuing 

 many diiferent directions decussate and change their 

 course. Plate III, fig. 2, page 187. Plate IV, figs. 

 1 and 2. 



243. Of the sphcriral, oval, and pyriforin nerre 

 cells. — The nerve cells belonging to this class have 

 a structure very difiereat from that of the caudate or 

 angular nerve cells. The fibres, instead of radiating 

 from the cells and appearing as if drawn out from 

 them, encircle them, and pursue a very circuitous 

 course after leaving the cell. They are curved and 

 coiled, and are of much greater length than is neces- 

 sary simply to traverse the space through which they 

 may be traced. The matter of which the fibres are 

 composed is continuous with that of the cell, and the 

 facts observed justify the inference that the fibres are 

 continually growing, or, in other words, that the matter 

 at the outer part of the cell gradually undergoes con- 



