SYSTEMATIC SCHOOL. 1 55 



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 

 natural selection in reproduction and derivation, and 

 applied this principle to all the phenomena of the 

 organic world, the systematic school was effectually 

 subdued by that same doctrine of Descent, thus fortified 

 and established, after which Lamarck had striven in 

 vain. The systematic school classified organisms accord- 

 ing to external and internal resemblances. Whence 

 this greater or smaller accordance, whence the gra- 

 dation 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 become the family, and the systematizers 

 have the plain task of restoring and combining the 



