JTEEVOUS SYSTEM AND GENUAL SENSATION. 



35 



nerves. It has been stated that 

 the mode of termination of the 

 primary fibres is much more 

 difficult of demonstration in the 

 central parts than in the peripheries. 

 It is impossible at present to say 

 positively that they again turn round 

 loop-wise, on the surface of the 

 brain, as certain observations would 

 lead us to conclude that they did. 

 (Fig. 14.) 



[ 83. Besides the tubular or 

 primary fibrous formations now 

 described, there is a second and 



general elementary structure in the 



,1 i ,1 

 nervous system, entitled the gang- 



home, or nervous globules, better the 

 ganglionic cells or corpuscles. These 

 corpuscles are met with in the brain, 



spinal cord, and ganglia, and also 



. \ 

 here and there in particular nerves. 



The cineritious, or grey nervous substance, wherever it occurs, be 



it deep seated or superficial, consists 



of aggregations of these ganglionic 



corpuscles. They have always a 



certain quantity, more or less, of the 



tubular or primary fibrous structure 



mixed with them ; the more abun- 



dant the primary fibres, the lighter 



is the mass ; the fewer they are, the 



darker is its colour. The ganglionic 



corpuscles, particularly in the brain 



and spinal cord, are much more de- 



licate and easily destroyed than the 



primary fibres. To study them, it is 



well to begin with the Gasserian 



ganglion of a small animal, such as 



a rabbit, or a thoracic ganglion of a 



small bird (figs. 1 6, B. 1 7, a). Here 



they mostly appear as globular or oval, nus, to show the course of the 



indistinctly granular bodies, having primary fibres 



Fig. 14. Central terminal 

 fibres from the yellow sub- 

 stance of the cerebellum of 

 the common pigeon : a, ter- 

 minal plexus of primary fi- 

 bres ; b, loopings of the ter- 

 minal fibres ; c, ganglionic 

 globules.* A ganglionic cell 

 from the Gasserian ganglion 

 of man, removed from its 

 sheath and highly magnified. 



tic nerve of the Fringilla spi 



D 2 



