154 



THE TISSUES. 



In figure 113 is shown a neurone with relatively small cell-body 

 and short dendrites, from the granular layer of the human cere- 

 bellum. 



The function of the dendrites has given rise to considerable dis- 

 cussion. Golgi and his school regard them as the nutrient roots of 

 the cell, a theory which is opposed by Ramon y Cajal (93, 1 ), van 

 Gehuchten (93, I), and Retzius (92, II). According to the latter, 

 all the processes of the nerve-cell are analogous structures ; they 

 pass out from a sensitive element, and probably have a correspond- 

 ingly uniform function. 



In the spinal ganglia and the homologous cranial ganglia, are 

 grouped the cell-bodies of neurones (peripheral sensory neurones, 

 peripheral centripetal neurones) which differ in many respects from 

 those above described. In the peripheral sensory neurones the 



Neuraxis. 



Telodendrion. 



Nucleus. 



Fig. 113. Nerve-cell with dendrites 

 ending in claw-like telodendria ; from the 

 granular layer of the human cerebellum ; 

 chrome-silver method ; X l Io - 



Fig. 114. Ganglion cell with a pro- 

 cess dividing at a (T-shaped process); from 

 a spinal ganglion of the frog ; X 2 3- 



neuraxes and dendrites have essentially the same structure, both 

 forming part of a nerve-fiber. From a relatively large, nearly round, 

 oval, or pear-shaped cell-body there arises a single process, which, 

 at a variable distance from the cell-body, divides into two branches 

 forming a right or obtuse angle with the single process (T-shaped 

 or Y-shaped division of Ranvier, 78). Both of these branches form 

 the central axis of a nerve-fiber ; one of the branches passing as a 

 nerve-fiber to the spinal cord or brain, as the case may be ; the other 

 forming a nerve-fiber which passes to the periphery. (Figs. 1 14 and 



115.) 



The ganglion cells of the spinal ganglia and homodynamic 

 structures of the brain are therefore apparently unipolar cells, but, 

 as Ranvier has shown, their processes are subject to a T-shaped or 

 Y-shaped division. The branches going to the periphery are re- 



