SUMMAR Y. 287 



had their influence. Nature is not a simple matter, 

 and there have doubtless been many laws at work in 

 producing evolution. Each of our investigators has 

 probably discovered a truth, and each is only in error 

 in believing the law he has discovered is of more 

 importance than the others. Certainly no one of all 

 these explanations is sufficient to account for the 

 question of the origin of species. But they are not 

 contradictory, and all may act together. Whether 

 with them all it can be believed that the origin of 

 species is cleared up, it is impossible to say. There 

 seem to be certain difficulties still existing, which 

 none of the above suggestions fully meet. But 

 neither of the series of data, variation or heredity, 

 are yet fathomed. Many laws have been discovered, 

 but there is yet room for others. And it is highly 

 probable that future study of these two subjects will 

 reveal factors yet unthought of, which have aided in 

 the origin of species. At present it must be ac- 

 knowledged that the problem is not solved, even 

 though evolution be accepted as a fact. 



