WHAT IS A SPECIES? 153 



its origin to this old school of philosophy, which recognized 

 the difference between the all and the parts, and found the 

 parts necessarily the changed forms of the all. The notion 

 of change of form, or Metamorphism, led to the seeking an 

 explanation of it; and the whole idea of evolution, or the un- 

 folding of things from that which they were not, grew up as 

 men thought on this subject. 



Antiquity of the Notion of Evolution. — As Schurman 

 pointed out in a chapter on Evolution and Darwinism in his 

 recent book on the " Ethics of Darwinism": " Like most of 

 the fundamental conceptions of our knowledge, and our 

 science, the essential elements of the theory [of evolution] 

 are as old as human reilection ; and among the Greeks we 

 find these five constituent elements of the modern evolution 

 hypothesis: The belief in the immeasurable antiquity of man, 

 the conception of a progressive movement in the life of 

 nature, the notion of a survival of the fittest, and the two- 

 fold assumption that any thing, or any animal, may become 

 another, since all things are at bottom the same."* 



Reality of Species Logically Antecedent to the Notion of Specific 

 Mutability. — But that particular form of the conception which 

 is formulated in the term inutahility of species was first clearly 

 expressed in the latter part of the last century, and for its 

 expression it was essential that first there should be a formu- 

 lated idea of the reality of species. The idea of organic species 

 had to be conceived of as a fundamental entity at the found- 

 ation of the science of organisms, before any explanation of its 

 origin, or of the laws governing its existence, could arise. 



The Idea of Species as Immutable. — The school of Linne 

 and Cuvier developed the idea of organic species, and in giv- 

 ing expression to the idea, which was abstract in itself, it 

 became necessary to find concrete delimitation of the species. 

 This idea of species is as essential to the biologist as the ideas 

 of atom, of molecule, of force, of energy, are to the physicist 

 and chemist ; and in the order of development of ideas, it was 

 natural that the primary definition of species should include 

 the idea of stability, and it was fully scientific too ; for, as 



* J. G. Schurman, " Ethics of Darwinism," pp. 43, 48. 



