436 A MANUAL OF VETERINARY PHYSIOLOGY 



the spinal cord to the foot, which would be actually long. This 

 type of cell is associated with motor nerves. Golgi cells of the 

 second type possess a short, widely-branched axon ; the axon 

 never leaves the grey matter, and this type of cell may be seen 

 in the cerebrum and cerebellum. Their short, widely-branching 

 axons lead to the belief that such cells are distributive in function. 

 The processes leading to a cell are called dendrites (Fig. 129). 

 Some cells, like the bipolar, have no such processes ; the multi- 

 polar, on the other hand, may be richly endowed. The neuro- 

 fibrils found in the cell extend into it from the dendrites. The 

 function of the dendrites is to collect impulses for transmission 

 to the cell. The other process belonging to a cell is termed the 

 axon (Figs. 127 and 129) ; it is the process which gives origin to 

 the nerve-fibre, and into its substance the neuro-fibrils from the 

 cell- body pass. Before the axon of a nerve becomes a nerve- 



Fig. 130. 



Cells from the Gasserian ganglion of a developing guinea-pig. The originally 

 bipolar cells are seen changing into cells apparently unipolar. The same 

 process occurs in the cells of the spinal ganglia (Van Gehuchten). 



fibre it gives off slender branches known as collaterals (Fig. 129) ; 

 they may be few in number or numerous, as in the case of Golgi 

 cells of the second type. A nerve-fibre terminates by ending 

 in a fine tuft of branches in the neighbourhood of another cell ; 

 the tuft is termed arborisation, and the junction thus formed 

 with the neighbouring cell is termed a synapse (Fig. 132). It is 

 believed that in the neighbourhood of synapses a receptive sub- 

 stance possessed of certain physiological properties exists which 

 favours the transmission of impulses to the neighbouring cell, with 

 which, it will be observed, it does not come into actual contact. 

 A nerve-cell, with its dendrites, axon, collaterals, and synapse, 

 constitute a neurone. A neurone is a nervous system in miniature ; 

 millions of such placed end to end, like the links in a chain, and 

 side by side, like a series of chains, enable the nervous system 

 to be visualised. Some of the links are short, others, we have seen, 

 are long, but no link — viz., no single neurone — runs from the brain 



