SYSTEMATIC SCHOOL. 155 



beyond an analogy, 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 reversed sequence of the layers 

 from inwards, outwards. The case, considered in the 

 abstract, appears highly complicated, and without a 

 prospect of solution; but it becomes marvellously 

 simplified, as we have already hinted, if the question 

 is thus generalized : In what manner are the still un- 

 differentiated terminations of the nerves affected by the 

 specific operation of the waves of light and sound, &c., 

 so as to assume the form and construction of specific 

 peripheral organs? It may be long before 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 natu- 

 ral selection in reproduction and derivation, and applied 

 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 vainly resisted, to the theory of transmuta- 

 tion. 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 funda- 

 mental 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 become the family, and the systematizers 

 have the plain task of restoring and combining the 



