188 THE FOUNDATIONS OF ZOOLOGY 



vincing those who deny the mutability of species, may not be, in 

 fact cannot be expected to be, the best for demonstrating the 

 value of natural selection to those who admit that species are 

 mutable. 



Before Darwin's day most systematic zoologists and botanists 

 believed that certain characteristics of each living being have 

 "specific value" while others are "varietal." The question how 

 you are to tell, from a single specimen, what characters are 

 specific and what varietal gave rise to interminable disputes, but 

 there was general agreement that the distinction exists in nature, 

 and that very dreadful consequences would attend doubt of its 

 reality. 



Specific characters, and those of generic or ordinal value as 

 well, were held to be immutable; and while the individual mem- 

 bers of a species were admitted to differ among themselves, or 

 to " vary," in characters which are not of specific, or more than 

 specific value, all were held to be exactly alike in their specific 

 characters, and also in all characters of generic or of still higher 

 taxonomic importance. 



As an exact science the Taxonomy of the last century is as 

 extinct as the dodo, for its very name is well-nigh forgotten; and 

 since few zoologists of the new school carry their so-called bibli- 

 ographical researches into the dust-covered books in which it is 

 entombed on the top shelves of old libraries, they fail to discover 

 that the words variety, vary, and variation were technical terms 

 when the " Origin of Species " was written. 



Of the twenty years and more which were devoted to the prepa- 

 ration of the book, many were spent in the study of domesti- 

 cated animals and cultivated plants, and in the comparison and 

 measurement of each species part by part. Darwin devoted him- 

 self to this work until he had obtained conclusive proof that 

 specific characters are as mutable as varietal characters, and until 

 he had shown that there is no organ or structure or marking 

 or measurement or habit or instinct which may not exhibit 

 diversity if many representatives of the species are carefully 

 compared. 



These observations and measurements, which were afterwards 

 published as a book under the title of "The Variation of Animals 



