316 



NERVE-CELLS. 



fibres are branched and united with neighbouring fibres, so as to form a network 

 along their course ; a condition which is never found in the course of the medullated 



Fig. 364. PORTION OF THE NETWORK OF FIBRES OF REMAK FROM THE PNEUMOGASTRIC 

 OF THE DOG (Ranvier). 



n, nucleus ; p, protoplasm surrounding it ; 6, striation caused by fibrils. 



Fig. 365. A SMALL BUNDLE OF NERVE FIBRES FROM THE SYMPATHETIC NERVE (Key and 



The bundle is composed of pale nerve-fibres, with the exception of the fibre in, m, which is enclosed 

 here and there by a thin medullary sheath ; n, n, nuclei of pale fibres. 



nerves. The branches of the olfactory nerve consist wholly of pale fibres, but these 

 are different from the ordinary pale fibres in being provided with a distinct nucleated 

 sheath. 



NERVE-CELLS. 



These are found in the grey matter of the brain and spinal cord and in the 

 ganglia ; they exist also in some of the nerves of special sense near their termina- 

 tions, and occur here and there in the course of certain other nerves. They are 

 often named ganglion-cells. 



In shape, nerve-cells vary greatly. Thus they may be spheroidal or ovoidal 

 with a general even outline, or they may be of an angular or irregular figure, and it 

 is found that the nerve-cells have a characteristic shape in certain parts of the 



