NERVE-CELLS. 



297 



fibres are especially abundant in the sympathetic trunks; 

 and they alone are found in the olfactory nerve. 



Nerve-Cells. As far as our knowledge at present goes, 

 all nerve -fibres begin as branches of nerve-cells. 



FIG. 87. Different forms of nerve-cells from the spinal cord. 1, a cell from 

 the anterior part of the gray matter, and believed to be connected with a motor 

 nerve-fibre; 2. a cell from.the posterior part of the gray matter, believed to be 

 connected with sensory fibres. 



At 1, Fig. 87, is shown a nerve-cell such as may be 

 found in the anterior part of the gray matter of the spinal 

 cord. It consists of the cell body, or cell protoplasm,, con- 

 taining a large nucleus, in which is a nucleolus. From the 



Describe a gray nerve-fibre. Where are they especially numerous ? 

 Name a cranial nerve that consists entirely of them. 

 How do nerve-fibres begin ? 

 Of what does a nerve-cell consist ? 



