THE REPRODUCTIVE FACTOR IN EVOLUTION. 



279 



tl\e_ influence of function and environment; but, without definitely 

 discussing the origin of variations, sought to show how the destructive 

 or eliminating, and the conservative or selecting agency of the 

 animate and inanimate environment, were the principal factors in 

 evolution. Given a sufficient crop of indefinite variations,— 

 unanalyzed or unanalyzable as to their origin, — the struggle for 

 existence separated the minority of wheat-ears from the majority of 

 tares, and secured a finer and finer harvest. 



So much had Darwin in his magistral labors to do with making the 

 general conception of evolution current coin, that we can readily 

 understand how not only the educated laity, but the majority of 

 professed naturalists, identified their adherence to the general doctrine 

 with a subscription to the specific principle of natural selection, and in 

 becoming evolutionists became at the same time Darwinians, that is to 

 say, natural selectionists. Of late years, however, as conflict has 

 passed from the outworks to the very citadel of evolution, — has come, 

 that is to say, to center round the problem of the origin of varia- 

 tions, — history has repeated itself. Naturalists such as Niigeli, 

 Mivart, and Eimer have championed the cause of internal organismal 

 variations, of evolution in terms of the constitution of the organism, of 

 progress according to the definite laws of organic growth. An active 

 school of neo-Lamarckians, such as Cope and Packard, has arisen in 

 America; while Spencer has re-emphasized the importance both of 

 function and of environment as factors in organic evolution, supported 

 moreover in this position by the experimental work of Semper and 

 others. The last published essays of Spencer may be referred to in 

 illustration of the unended state of the controversy, but at the same 

 time of the growing tendency to limit the importance of natural 

 selection, and as a good instance of successful endeavor to recognize 

 the measure of truth in the different theories. Wallace remains 

 staunchest among the upholders of the theory of natural selection, for 

 his share in which he seems ever to refuse to take to himself sufficient 

 credit; but it is interesting to notice, that in his recent valuable work, 

 in re-inforcing his old objections against the importance which Darwin 

 attached to sexual selection, he has made admissions welcome to those 

 of us who believe that the shoulders of natural selection have also been 

 overburdened. As we have already noticed, the phenomena of male 

 ornament are discussed and summed up as being ' ' due to the general 

 laws of growth and development," and as such that it is " unnecessary 

 to call to our aid so hypothetical a cause as the cumulative action of 

 female preference. ' ' Again ' ' if ornament is the natural product and 

 direct outcome of superabundant health and vigor," — a view to which 

 the reader of the preceding pages can be no stranger, — "then no 



