Bailey.] *^^ [May 1, 



variations, perhaps even adaptations, were the result of extrinsic factors 

 acting upon tlie organism, and that these variations or adaptations were 

 increased and improved by natural selection. This is, I believe, the 

 only ground which is at present tenable, and it is but another testimonj'^ 

 to the greatness of that man of men, that, after exploring for a score of 

 years all the ins and outs of pure selection and pure adaptation, men 

 are now coming back to the position outlined and unswervingly main- 

 tained by him. 



Finally, we ought not to suppose that we have already reached a 

 satisfactory solution of the evolution problem, or are, indeed, near such 

 a solution. "We must not conceal from ourselves the fact," says Roux, 

 "that the causal investigation of organism is one of the most difficult, 

 if not the most difficult, problem which the human intellect has at- 

 tempted to solve, and that this investigation, like every causal science, 

 can never reach completeness, since every new cause ascertained oul}" 

 gives rise to fresh questions concerning the cause of this cause." 



The Factors of Organic Evolution from a Botanical Standpoint. 



By Prof. L. U. Bailey. 



(Read before tlie American PhilosopJucal Society, May 1, 1S96.) 



THE SURVIVAL OF THE UNLIKE. 



We all agree that there has been and is evolution ; but we probably 

 all disagree as to the exact agencies and forces which have been and are 

 responsible for it. The subject of the agencies and vehicles of evolution 

 has been gone over repeatedly and carefully for the animal creation, but 

 there is comparatively little similar research and speculation for the plant 

 creation. This deficiency upon the plant side is my excuse for calling 

 your attention, in a popular way, to a few suggestions respecting the con- 

 tinuing creation of the vegetable world, and to a somewhat discursive 

 consideration of a number of illustrations of the methods of advance of 

 plant tj'pes. 



1. Nature of the Divergence of the Plant and Animal. 



It is self-evident that the development of life upon our planet has taken 

 place along two divergent lines. These lines originated at a common 

 point. Tliis common life-plasma was probably at first more animal like 

 than plant-like. The stage in which this life-plasma first began to assume 

 plant-like functions is closely and possibly exactly preserved to us in that 

 great class of organisms which are known as mycetozoa when studied by 

 zoologists and as myxomycetes when studied by botanists. At one stage 



