16 SCIENCE PROGRESS 



the commonly accepted order of evolution, have not been 

 touched upon at all. Meanwhile almost daily new knowledge is 

 being gained, and new light being thrown upon these problems, 

 and although in some cases the new facts seem to find no place 

 ready for them in the theory, and although in others they lead 

 to a recasting of many of our ideas, yet progress is continuous, 

 and there can be no doubt that in course of time many of the 

 most puzzling facts will find a natural explanation as the theory 

 developes. 



