1 



SECTION II. 



THE EXPLANATORY DOMAIN OF THE HYPOTHESIS 

 OF EVOLUTION. 



CHAPTEK I. 



INTRODUCTION. 



ACCORDING to what we have so far stated in connection 

 with palaeontology the object of an evolutionary or 

 transformation hypothesis is fairly well defined. 



In the first place we have to inquire, by observa- 

 tion of, and experiment with, the organisms of to-day, 

 whether they are generally capable of transformation, 

 what causes are thereby involved, and of what kind 

 are the changes ascertained. 



Thereby we arrive at the first and entirely indispen- 

 sable basis of any attempt whatever at scientific ex- 

 planation through observation. The second part of the 

 task involved would be to imagine the same causes as 

 effective in the past, alone or in connection with other 

 influences of similar kind, and then to compare the 

 chronologically successive organisms of ascertainable 

 form and structural conditions with those still subject 

 to observation. If both show the same peculiarities, 

 then we may conclude with perfect right that the modi- 

 fications of the primeval animals and plants were really 

 brought about by those causes or, better expressed, 



