36 Charles Robert Darwin. 



making it more perfect and with every stroke confirming 

 his opinions. Thus, for example, Professor Agassiz pro- 

 duced no greater work than his "Essay on Classification." 

 You know that he Avas strenuously opposed to Darwin's 

 theor}-. But his Essay on Classification was unwittingly 

 an argument in its behalf. ]\Ir. John Fiske informs us 

 that it was convincing to him of organic evolution before 

 Darwin's book appeared. But let us see how it is that a 

 system of classification is an argument for organic evolu- 

 tion. 



The classification of plants and animals has occupied the 

 scientific mind for many centuries. The earliest classifica- 

 tions were all popular and semi-popular ; that is to say, they 

 were based upon external resemblances. A whale was 

 called a fish because it had the general form and habits of 

 a fish. Even the great Buffon questioned whether a croc- 

 odile should not be classified as an insect because the hard- 

 ness of its casing corresponds to the hardness of a beetle's. 

 He finally decided that the crocodile is not an insect, and 

 for this reason : the crocodile is so large an animal that it 

 would make " altogether too terrible an insect " ! 



The endless confusion growing out of such a superficial 

 method suggested to Linngeus that internal structure rather 

 than external appearance should be made the basis of class- 

 ification. At once the sky began to clear. A natural sys- 

 tem was worked out. It proved to be a tree-like system. 

 A short trunk represents the lowest organisms, concerning 

 Avhich, when challenged, " Vegetable or Animal ? " we can- 

 not say. This trunk soon separates into two great branches, 

 one for the animal, the other for the vegetable, kingdom. 

 Smaller branches springing from these represent classes ; 

 smaller from these, families ; then orders, genera, and 

 species bring us to the smallest branches, twigs, and leaves. 

 Now, in this tree-like system we have just such a system 

 as the evolutionist would naturally expect. It is " as clear 

 an expression as anything could be of the fact that all 

 species are bound together by the ties of genetic relation- 

 ship." Work it backward or forward and we get the same 

 impression : forward, the gradual shading off of characters 

 into forms more and more specialized is eloquent for the 

 fact of transmutation; backward, the difficulty of deter- 

 mining the genus, order, class, of certain organisms of the 

 humblest grades is most instructive. Proof there may not 



