SYSTEMATIC SCHOOL. 



155 



ogy, though a striking one. It is only the microscopic 

 structure of the nerve membrane, which is extremely 

 similar in both divisions, with the exception of the re- 

 versed sequence of the layers from inwards, outwards. 

 The case, considered in the abstract, appears highly com- 

 plicated, and without a prospect of solution; but it be- 

 comes marvellously simplified, as we have already hinted, 

 if the question is thus generalized: In what manner are 

 the still undififerentiated terminations of the nerves af- 

 fected by the specific operation of the waves of light 

 and sound, &c., so as to assume the form and construc- 

 tion of specific peripheral organs? It may be long be- 

 fore these relations are fathomed; our only concern is 

 to defend the theory from the reproach of inadequacy, 

 by showing the scope for investigation according to our 

 point of view. 



When Darwin had brought to light the effects of 

 natural selection in reproduction and derivation, and ap- 

 plied this principle to all the phenomena of the organic 

 world, the Doctrine of Descent, thus fortified and estab- 

 lished, practically subdued the systematic school which 

 Lamarck had vainjy resisted, to the theory of transmu- 

 tation. The systematic school classified organisms ac- 

 cording to external and internal resemblances. Whence 

 this greater or smaller accordance, whence the grada- 

 tion and the heterogeneity, it knew not how to tell. It 

 was thought that much was gained when the fundamental 

 forms of types were spoken of, even though no account 

 was given of the intrinsic nature of these types, floating 

 like ideas above the phenomena. Now the type has be- 

 come the family, and the systematizers have the plain 

 task of restoring and combining the pedigrees of the 



