CHAP. II.] A NERVOUS SYSTEM. 89 



united to one another by means of a network of slender 

 ramifying fibrils (fig. 9), and in part of an interspersed homo- 

 geneous or simply granular basis substance. It has been 

 long known to contain some small 

 branched corpuscles, almost indis- 

 tinguishable from young nerve 

 cells ; and of late the much 

 branched processes of many fully 

 developed nerve cells have also 

 been thought to have a structural 

 continuity with this minute net- 

 work of the neuroglia. If these 



, . FIG. 9. Portion of Neuroglia 



observations are correct, portions from the s P mai cord, open 

 of the 'intermediate substance ' mes , hes are s .f n f with , sm f 



nuclei or cells at intervals, 



WOllld Often Constitute part Of the but at two places close lamelli- 

 , IT form interlacements are shown. 



circuits traversed by nerve currents (K 6iiiker.) Magnified 350 dia- 



in their passage through the meters - 



centres. 



This intermediate tissue is, in short, the probable matrix 

 wherein and from which new nerve fibres and new nerve 

 cells are evolved in animals, of whatsoever kind or degree of 

 organization, during their advance in reflex, in instinctive, 

 or in intellectual acquirements. Some such process must 

 take place, pari passu with the acquisition of new know- 

 ledge and powers, of all kinds and howsoever acquired : 

 whether it comes, as in lower animals, from mere intercourse 

 with natural phenomena ; or, as amongst ourselves, from 

 similar means, supplemented by individual application in 

 ' the mastery of educational or professional pursuits and of 

 all kinds of handiwork ; or whether the new knowledge and 

 powers come to us as a result of that more general edu- 

 cation or ' experience ' which is gained by daily intercourse 

 with the pleasures, troubles, turmoils, and exertions in- 

 separable from social life. The acquirement of new powers 



