THE NERVES. 



95 



the cells are classified as unipolar, bipolar, or multipolar. These 

 processes are of two kinds one kind dividing and subdividing 

 (branching processes) until they become very delicate and seem to 



FIG. 24. 





Nerve-cells from the Anterior Horn of Gray Substance of the Spinal Cord. 



join with the equally fine processes from other cells ; another class 

 (axis-cylinder processes) pass on without division, and become axis- 

 cylinders of medullated nerve-fibres. 



The nerve-cells vary greatly in size, and are very diverse in 

 form, but the presence of nucleus and nucleolus and of the pro- 

 cesses is characteristic of nerve-cells. They may be enclosed in a 

 delicate capsule which becomes continuous with the neurilemma 

 (Fig. 25). 



What is the function of the nerve-fibres ? 



The transmission of a stimulus. The axis-cylinder connects 

 the centre and periphery cells, and conveys between them the 

 stimuli. This transmission for any particular fibre is in one direc- 

 tion only. 



How may the nerve-fibres be classified? 



Into afferent (or centripetal) and efferent (or centrifugal) fibres. 



