44 BIOLOGICAL SOCIETY ()F WASHINGTON. 



clone natural selection will" continue to lack a solid basis upon 

 which to rest. 



But it seems to me that there is an answer to the objection, 

 and one which fully meets it. This answer is nothing more 

 nor less than the patent fact already stated that fortuitous vari- 

 ation actually does go on at all times, in many directions, and 

 to great lengths, without any perceptible change in the degree 

 of adaptation which the varying forms have to their environ- 

 ment. I have shown how this takes place in one important 

 genus of plants, and it would be easy to extend the observa- 

 tion to almost any other genus. I doubt not that the animal 

 kingdom is also full of examples. 



Here then we have the solution of by far the worst difficulty 

 in the way of natural selection. The beneficial effect need not 

 be assumed to begin at the initial stage. It need not be felt 

 until well-formed varieties have been developed without regard 

 to any advantage in the particular differences which they pre- 

 sent. There seems to be no flaw in this mode of solving this 

 paramount problem, and if it is objected that it amounts to a 

 new explanation of the origin of species, I am ready to admit 

 it, and I believe that more species are produced by fortuitous 

 variation than by natural selection. Natural selection is not 

 primarily the cause of the origin of species ; its mission is far 

 higher. It is the cause of the origin of types of structure, such 

 as those whose history I have endeavored to trace, and through 

 which alone biologic evolution takes place. 



Extra-Normal Influences in the Vegetable Kingdom. — Re- 

 turning from this important digression to the subject of extra- 

 normal influences in the vegetable kingdom, let us inquire 

 more closely into their exact nature. As already remarked, 

 the most important are those which have resulted in the devel- 

 opment of beaut\- and fragrance in flowers and of bright colors 



