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 
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 
