lOOO 



HUMAN ANATOMY. 



Fig. 840. 



connected with the acoustic nerve. An interesting modification of bipolar neurones 

 is presented by the olfactory cells, whose dendrites are represented by the extremely 



short processes embedded within the nasal mucous 

 membrane, whilst the axones are prolonged as the 

 fibres of the olfactory nerves into the cranial cavity 

 to end in telodendria within the glomeruli of the 

 olfactory bulb. 



The cell-bodies of the multipolar neurones, 

 which possess one axone and several dendrites, vary 

 in form (Fig. 841). Some, as those within the sym- 

 pathetic ganglia, are approximately spherical and of 

 moderate size, with short delicate dendrites ; many 

 are of large size and irregularly stellate form, the 

 dendrites passing out in all directions, as seen in the 

 conspicuous motor neurones within the gray matter 

 of the spinal cord ; others possess a regular and 

 characteristic form, as the flask-shaped cells of Purkinje 

 within the cerebellum, or the pyramidal cells of the 

 cerebral cortex. Certain multipolar neurones within 

 the cerebral cortex, and especially those constituting 

 the chief components of the granule layer of the 

 cerebellum, are distinguished by the small size of 

 their cell-bodies and the peculiar ramifications and claw-like telodendria of their 

 dendrites (Fig. 945 j. Within the cerebellar cortex are likewise found examples of 



Bipolar neurones; a, from olfactory 

 mucous membrane — dendrite is above; 

 by from retina. (Modified from Cajal.) 



Fig. 841. 



Multipolar nerve-cells of various forms ; A , from spinal cord ; B, from cerebral cortex ; C from cerebellar cortex 



(Purkinje cell) ; a, axone ; c, implantation cone. 



the multipolar neurones of Golgi's type II, whose axones almost immediately 

 undergo elaborate branching within the gray matter to which they are confined. 

 The Nerve-Fibres. — From the foregoing considerations it is evident that the 

 nerve-fibres are not independent elements, but that all are the processes of neurones 

 — either the axones of those that are prolonged into fibres (type I), or the dendrites 

 of those situated within the spinal and other sensory peripheral ganglia. Although 

 neurones exist which are not continued as nerve-fibres, the latter are always connected 



