564 CONNEXION OF THE NERVES WITH THE CORD. 



ganglia exist in an isolated state, but are made to approach each 

 other in the more perfect development of the animal and become 

 fixed into a sort of spinal marrow, without any impairment of 

 their functions. 



The function of the gray matter of the spinal cord, may 

 nevertheless be precisely the same in man, as though it was 

 divided into separate masses. It has before been shown that 

 no communication takes place laterally between the fibres of 

 the medullary matter, however closely they may run in con- 

 junction, their neurilematic covering isolating them from each 

 other. The same may take place in regard to the globules of 

 cineritious matter, each of which is surrounded and separated 

 from the rest by a cellular envelop, and appears, as shown by 

 the microscopical observations of Remak and Miiller, to act an 

 independent part in giving origin to an individual medullary 

 fibre. 



Connexion of the Nerves with the Cord. 



In this granular mass of cineritious substance in man and the 

 inferior animals, there are no fibres of any description to be 

 seen in a longitudinal section. But in a transverse cut, as has 

 been pointed out by Bellingeri, Mayo, and Grainger, a spotted 

 appearance is presented, in consequence of the intermixture of 

 the white fibres with the gray-substance. " The source and 

 connexion of the white fibres," says Grainger,* " thus placed 

 within the gray, are not known ; but it is certain that they must 

 in part, if not entirely consist of certain fibres, which pass into 

 the gray substance from the spinal nerves." He believes 

 the peculiar crescentic shape of the gray matter depends upon 

 the anatomical connexion of the nerves ; some of the fibres of 

 both the anterior and posterior roots, passing into the gray 

 substance, the junction of which is favored by one horn 

 being turned forward and the other backward. After repeated 

 examination, in man and the superior animals, Mr. Grainger, 

 appears to have fully verified the opinion, entertained by most 



* Ob. citat. 



