WHAT IS EVOLUTION? 29 



ways to the solution of many questions more or less 

 analogous to that of the origin of species, while, as was 

 natural, it has been pushed in a vast number of wild 

 and extreme directions by popular writers not con 

 versant with science in a practical manner. It has, 

 however, been seriously canvassed by the more 

 cautious and conservative men of science, and has 

 been found to fit in so badly with what is actually 

 known of nature, that it has gradually been obliged to 

 modify its claims ; and ultimately its adherents have 

 become divided into distinct schools, differing materi 

 ally from each other and from the original Darwinism, 

 though all agree in claiming Darwin as a master and 

 in upholding his merit as a great discoverer. These 

 various schools are divided: (i) As to the primary 

 causes of the development ; (2) As to the secondary 

 causes ; (3) As to the mode or modes. 



With reference to the first, there are some evolu 

 tionists who are agnostic like Spencer, monistic like 

 Haeckel, or merely negatively materialistic, like a 

 large number of the younger naturalists. On the other 

 hand, there are advocates of evolution who profess to 

 see in it the manifestation of Divine creative power, 

 and with whom evolution is merely the manner in 

 which the will of God manifests itself. 



With reference to the secondary causes supposed 

 to be at work, observation and experiment have 

 shown that, if development of new species has taken 

 place, other causes than those alleged by Darwin 



