(00 



The Plant World. 



to keep an open mind as to the larger meanings of the results 

 obtained, and this epoch-beginning work may also be taken to 

 represent the culmination and finale of the observational method 

 in dealing with nature, representing its highest possible realiza- 

 tion. When the general state of biological knowledge is taken 

 into consideration, it may be regarded as conclusive that never 

 again will anything of comparable importance, in impulse or 

 achievement be accomplished in this manner. 



In addition to the inadequacy of observational methods 

 for detecting causes and effects at first hand, the results obtained 

 have the inherent weakness of being difficult to duplicate, since 

 the would-be observer who seeks to confirm them must wait 

 upon a concurrence of events simulating those of the original 

 observation. In the case of the great range of facts cited by 

 Darwin, anything like corroboration, except in a fragmentary 

 way, was humanly impossible, the energy of a large ruimber of 

 interested workers being absorbed for nearly half a century in 

 poorly rewarded attempts to verify observations cited in support 

 of natural selection. Such duplications which might never be 

 more than partial in their completeness under the most favorable 

 circumstances, yielded but little in support of the main idea, 

 and gave scant aid in the development of its more important 

 corollaries. Neither verification nor refutation being attainable, 

 vritings on evolution during this period, in greater part, took 

 on the form of concordances of Darwinism and of critiques upon 

 the probable and possible meanings of passages in his writings, 

 together with much controversial display and attenuated de- 

 duction, altogether constituting a situation which goes far to 

 justify the position of Bateson and others, that the immediate 

 effect of Darwinism was to stifle instead of stimulating research, 

 a criticism levelled at Darwin but which in reality is a character- 

 ization of the lack of development of biological science. The 

 immediate contributions of value following upon and consequent 

 upon Darwinism consist of alternate interpretations of descent 

 and substitute hypotheses as to orthogenesis, definiteness of 

 variation, environic relations and mechanism of heredity pro- 

 duced by the more vigorous thinkers during the period 

 following the establishment of the theory of descent. 



