STRUCTURE OF NERVE-CENTRES. 



475 



" The vesicular nervous substance is composed, as its name 

 implies, of vesicles or corpuscles, which are commonly 

 called nerve-corpuscles, or ganglion-corpuscles. These are 

 found chiefly in the nervous centres, i.e., the brain, spinal 

 cord, and the various ganglia, but occasionally also in 

 the nervous trunks ; they are mingled with nerve-fibres, 

 and imbedded in a dimly-shaded or granular substance ; 

 they give to the ganglia and to certain parts of the brain 

 and spinal cord the peculiar greyish or reddish-grey aspect 



Fig. 131.* Fig. 132. f 



by which these parts are cha- 

 racterized. They are large, 

 nucleated cells, filled with a 

 finely granular material, some 

 of which is often dark like 

 pigment : the nucleus, which 

 is vesicular, contains a nucle- 

 olus(fig. 131). Besides vary- 

 ing much in shape, partly in 

 consequence of mutual pressure, they present such other 

 varieties as make it probable either that there are two 



* Fig. 131. Nerve-corpuscles from a ganglion (after Valentin). In 

 one a second nucleus is visible. In several the nucleus contains one or 

 two nucleoli. 



f Fig. 132. Stellate or caudate nerve-corpuscles, with tubular pro- 

 cesses issuing from them. Besides being filled with granular material 

 continuous with the contents of the processes, the corpuscles contain 

 black pigment-matter (after Hannover). 



