28 



ANATOMY OF THE CENTRAL NERVOUS SYSTEM. 



arises always a single immense branch, which after a short course divides- 

 into one fiber, which, at the periphery of the ganglion, passes o^^t as neu- 

 raxon, and one fiber, which remains within the ganglion, rapidly dividing 

 into twigs. The neuraxon passes either direct (Fig. 8, e) into a nerve, in 

 which case it is probably of motor natnre, or it passes into a commissural 

 nerve, which joins with the ganglion, with those located farther anterior 

 or posterior, as is the case with all neuraxons from the very large cells (Fig. 

 8, d and / ). The neuraxon may pass along the same side (d) or it may cross 

 over to the opposite side (/). From the neuraxon the dendrites branch 



Fig. 9. — From the cornu Ammonis of the rabbit. A, Composite figure from 

 preparations by S. R. j Cajal. ci, li, c, Association-cells whose long neuraxons 

 split up into moss-like twigs, which invade the layer of pyramidal cells (A). 

 At the left is a completely-sketched pyramidal cell. Through its descending 

 neuraxon it is in relation with the "brain-pith" and through its ascending den- 

 drites it is in relation with other systems and cells not figured. Through the asso- 

 ciation-cells many pyramidal cells are brought into combination. 



off and pass into the substance of the ganglion. In their finer ramifications 

 they are well adapted to connect together the separate elements of the 

 whole ganglion. 



In the fine net-work which they form, appear nerve-fibers which come 

 either from the peripheral-sensory nerves (2 a), or come from other ganglia 



