FUNCTIONS OF THE NERVOUS SYSTEM. 



Fig. 8. 



Primitive fibres and ganglionic globules. A, from sympathetic ganglion ; * a separate vesicle, showing 

 its pellucid nucleus and nucleolus. B, from gray substance of human cerebellum ; a, 6, plexus of primitive 

 fibres; c, nucleated globules: * a separate globule from human Gasserian ganglion. 350 Diam. (After 

 Wagner.) 



masses, with which the nervous trunks are connected. It forms the centre of 

 the ganglia, which are the centres of the nervous system in the Invertebrata : 

 it occupies part of the interior of the spinal cord of Vertebrate d animals, which 

 may be regarded as a chain of similar ganglia; and in the distinct ganglia 

 which occur among the latter, it holds the same relative position. In the brain 

 of Vertebrata, however, it is disposed externally, and forms a sort of coating to 

 the mass beneath, which almost entirely consists of fibrous structure ; hence it 

 has been called the cortical substance, whilst the fibrous portion has been 

 termed medullary matter. The ganglion-globules (Figs. 8 and 9) are usually 

 from l-300th to l-1250th of an inch in diameter ; possessing a spherical or 

 oval form, more or less flattened ; and having a reddish colour, to which the 

 characteristic hue of the ganglionic substance (whence it has received the ap- 

 pellation cineritious) is chiefly owing. Each contains one or more nuclei with 

 subordinate nucleoli; and is enclosed in a very fine filamentous investment, in 



Primitive fibres and ganglionic globules of human brain, after Purkinje. A, gangl'onic globules lying, 

 amongst varicose nerve-tubes, and blood-vessels, in substance of optic thalamus; a, globule more enlarged; 

 6, vascular trunk. B, B, globules with variously-formed peduncles, from dark portion of crus cerebri. 350 

 Diara. (After Wagner.) 



