350 BIOLOGY AND ITS MAKERS 



This is not the place, however, to deal with the technical 

 aspects of the discussion of the factors of organic evolution; 

 it is rather our purpose here to give a descriptive account of 

 the theory and its various explanations. First we should 

 aim to arrive at a clear idea of what the doctrine of evolution 

 is, and the basis upon which it rests; then of the factors which 

 have been emphasized in attempted explanations of it; and, 

 finally, of the rise of evolutionary thought, especially in the 

 nineteenth century. The bringing forward of these points 

 will be the aim of the following pages. 



Nature of the Question. — It is essential at the outset to 

 perceive the nature of the question involved in the theories 

 of organic evolution. It is not a metaphysical question, ca- 

 pable of solution by reflection and reasoning with symbols; 

 the data for it must rest upon observation of what has taken 

 place in the past in so far as the records are accessible. It 

 is not a theological question, as so many have been disposed 

 to argue, depending upon theological methods of interpreta- 

 tion. It is not a question of creation through divine agencies, 

 or of non-creation, but a question of method of creation. 



Evolution as used in biology is merely a history of the 

 steps by which animals and plants came to be what they are. 

 It is, therefore, a historical question, and must be investigated 

 by historical methods. Fragments of the story of creation 

 are found in the strata of the earth's crust and in the stages 

 of embryonic development. These clues must be brought 

 together; and the reconstruction of the story is mainly a 

 matter of getting at the records. Drummond says that evo- 

 lution is "the story of creation as told by those who know 

 it best." 



The Historical Method. — The historical method as ap- 

 plied to searching out the early history of mankind finds a 

 parallel in the investigations into the question of organic 

 evolution. In the buried cities of Palestine explorers have 



