Darwinism. 1 8 1 



Heat, cold, food supply, geographical distribution, 

 winds, water supply, prevalence of certain birds or 

 other animals, all these are the factors which must 

 be taken into consideration when studying this 

 problem and in trying to trace out definite results. 



Huxley, in defining Darwin's hypothesis, says: 

 " As I apprehend it, it is that all the phenomena of 

 organic nature, past and present, result from, or are 

 caused by, the interaction of those properties of 

 organic matter, which we have called Atavism and 

 Variability, with the Conditions of Existence ; or, in 

 other words given the existence of organic matter, 

 its tendency to transmit its properties, and its ten- 

 dency occasionally to vary ; and, lastly, given the 

 conditions of existence ; by which organic matter 

 is surrounded that these put together are the 

 causes of the Present and of the Past conditions of 

 Organic Nature." 



Darwin himself says : " No one ought to feel sur- 

 prise at much remaining as yet unexplained in regard 

 to the origin of species and varieties, if he makes due 

 allowance for our profound ignorance in regard to 

 the mutual relations of all the beings which live 

 around us. Who can explain why one species ranges 

 widely and is very numerous, and why another allied 

 species has a narrow range and is rare ? Yet these 

 relations are of the highest importance, for they 

 determine the present welfare, and, as I believe, the 

 future success and modification of every inhabitant 

 of this world. Still less do we know of the mutual 

 relations of the innumerable inhabitants of the world 

 during the many past geological epochs in its his- 



