U4 



The Plant Worlb 



an interesting future possibility that the theory of the building 

 up of adaptations out of the natural selection of undirected 

 variations, to use my colleague's language, may prove to be a 

 dogma quite as unsupported by facts as the Lamarckian dogma 

 of the inheritance of acquired characters. I long ago pointed 

 out that a very large number of new characters in the hard parts 

 of mammals are adaptive in direction from the beginning; I am 

 very far from saying that all new characters are adaptive in 

 direction; I only make this statement as to those characters I 

 have had the opportunity of repeatedly observing. 



"I now challenge the zoologists to produce a single instance 

 of a series of animals in which adaptive characters are being 

 accumulated through the selection of undirected variations, i. e., 

 of variations which are thoroughly mixed up, in which there is 

 no law evident. Such a series has never been produced by any- 

 one. Of course I bar from this challenge orthogenic changes 

 of character under environmental influences. I refer to the 

 pure Darwinian hypothesis. The hypothesis is still as Darwin 

 left it, an ingenious working theory, awaiting either experimental 

 evidence or evidence of any kind. 



"While the 'philosophic zoologist' of today has made his 

 choice, the philosophic paleontologist has also made his choice. 

 The latter certainly does not find direction in the old teleologic 

 sense, but quite as certainly he finds no evidence of such fortuity 

 as will justify the use of the word undirected as furnishing ma- 

 terials for natural selection. The materials for natural selection 

 are furnished by the ensemble of an enormous number of charac- 

 ters, each of which is a unit pursuing its independent history 

 and fluctuating and mutating and moving in direct lines under 

 laws which the philosophic paleontologist has proof of, but total- 

 ly fails to understand. Consequently he assumes the agnostic 

 position that there is some principle, or principles of direction, 

 or better — to use Prof. Morgan's own words — ' unknown agencies ' 

 still to be discovered other than the principle of order coming 

 out of fortuitv." 



