434 



THE TISSUES. 



no longer present any trace of a double contour, the medulla being 

 coagulated. 



5. What is called neuroma is decided by Wedl to be, sometimes 

 at least, a cancerous deposit in the continuity of a nerve. 



6. A new formation of fine nerve-fibres was noticed by Yirchow 

 in pleuritic and peritoneal adhesions. 



- 

 II. CELLULAR (vesicular) NERVE-TISSUE, or NERVE-CELLS. 



The nerve-cells (nerve-corpuscles, Valentin) vary extremely in 

 their size ; occurring, like the nerve-fibres, as large, small, and in- 

 termediate. The extremes are g^^, and 2 ^<y of an inch. The 

 nuclei are from HTr Vtf to ^VTT of an inch, and the nucleoli 5^0 to 

 4 ATT of an inch in diameter. 



Many varieties of /orw, are also presented by the nerve-cells. 

 (Figs. 279 and 280). The spherical form (apolar cells) occurs more 



Fig. 279. 



C D E 



Various forms of nerve-cells. A, B. Large stellate cells with their prolongations ; from the anterior 

 horn of the gray matter of the spinal cord. c. Nerve-cell with its connected fibre ; from the anasto- 

 mosis of the facial and auditory nerves at the meatus anditorius internus of the ox. a. Cell-wall. 

 b. Cell-contents, c. Pigment, d. Nucleus, e. Prolongation forming the neurilemma,/, of the fibre. 

 D Nerve-cell from the'substantia ferruginea of man. E. Smaller cell from the spinal cord. (Mag- 

 nified 350 diameters.) 



/ 



abundantly in the ganglia ; but the original form of most nerve- 

 cells is modified by prolongations poles, or pale processes. Of 

 these there may be from 1 to 5, or even 8 ; hence the cells are 

 termed uni-, bi-, tri-, or multi-polar. These processes are also fre- 

 quently branched. (Fig. 280.) There are, however, no cells with 

 branched processes in the ganglia; but only those having 1 to 4 

 pale processes, and which are continuous with dark-bordered nerve- 

 fibres. 



