August 30, 1889.] 



SCIENCE. 



151 



it is hard to say whether we should most admire the intellectual or 

 the moral qualities which, in relation to their common labors, they 

 have displayed. 



Now, I have sought to lay emphasis on this the dramatic side of 

 " Darwinism," because in the work which under this title I am 

 about to review, it appears to me that Mr. Wallace has added yet 

 another scene, or episode, which, in the respects we are consider- 

 ing, is quite worthy of all that has gone before. I do not allude 

 merely to the fact that in this work we have the matured conclu- 

 sions of the joint-originator of Darwinian doctrine, published most 

 opportunely at a time when biological science is especially anxious 

 to learn his views upon certain questions of the highest importance 

 which have been raised since the death of Darwin ; nor do 1 allude 

 merely to the further fact that in now speaking out, after nearly a 

 decade of virtual silence on scientific topics, the veteran naturalist 

 has displayed an energy of investigation as well as a force of 

 thought which is everywhere equal to, and in many places sur- 

 passes, anything that is to be met with in all the solid array of his 

 previous works. That these facts present what I call the dramatic 

 side I fully allow ; but the point which in this connection I desire 

 to bring into special prominence is the following. 



It is notorious that, from the time when they published their 

 joint theory of evolution by natural selection, Darwin and Wallace 

 tailed to agree upon certain points of doctrine, which, although of 

 comparatively small importance in relation to any question of evo- 

 lution considered as a tact, were, and still continue to be, of the 

 highest possible importance in relation to the question of evolution 

 considered as a method ; i.e., in relation to the causes or factors 

 which have been concerned in the process. It was the opinion of 

 Mr. Darwin that natural selection has been the chief, but not the 

 only, cause of organic evolution ; while, in the opinion of Mr. Wal- 

 lace, natural selection has been the all and in all of such evolution, — 

 virtually the sole and only principle which has been concerned in 

 the development both of life and of mind from the amceba to the 

 ape, — although he further and curiously differs from Darwin in 

 an opposite direction, by holding that natural selection can have 

 had absolutely no part at all in the development of faculties dis- 

 tinctively human. Disregarding the latter and subordinate point of 

 difference, — a re-presentation of which in the concluding chapters 

 of his present work, 1 may however remark, appears to me sadly 

 Hke the feet of clay in a figure of iron, marring by its manifest 

 weakness what would otherwise have been a completed and self- 

 consistent monument of strength, — let us first clearly understand 

 to what it is that the major pomt of difference amounts. This may 

 best be done by quoting from each of the authors in question par- 

 allel passages, which occur m the concluding paragraphs of their 

 latest works. 



Mr. Darwin writes : " I have now recapitulated the facts and 

 considerations which have thoroughly convinced me that species 

 have been modified during a long course of descent. This has 

 been effected chiefly through the natural selection of numerous 

 successive, slight, favorable variations, aided in an important man- 

 ner by the inherited effects of the use and disuse of paits ; and in 

 an unimportant manner, that is in relation to adaptive structures, 

 whether past or present, by the direct action of external conditions, 

 and by variations which seem to us in our ignorance to arise spon- 

 taneously. It appears that I formerly underrated the frequency 

 and value of these latter forms of variation, as leading to perma- 

 nent modifications of structure independently of natural selection. 

 But as my conclusions have lately been much misrepresented, and 

 it has been stated that I attribute the modification of species ex- 

 clusively to natural selection, I may be permitted to remark that in 

 the first edition of this work, and subsequently, I placed in a most 

 conspicuous position — namely, at the close of the introduction — 

 the following words : ' I am convinced that natural selection has 

 been the main, but not the exclusive, means of modification.' This 

 has been of no avail. Great is the power of steady misrepresenta- 

 tion ; but the history of science shows that fortunately this power 

 does not long endure." 



Mr. Wallace writes : " While admitting, as Darwin always ad- 

 mitted, the co-operation of the fundamental laws of growth and 

 variation, of correlation and heredity, in determining the direction 

 of lines of variation or in the initiation of peculiar organs, we find 



that variation and natural selection are ever-present agencies, 

 which take possession, as it were, of every minute change origi- 

 nated by these fundamental causes, check or favor their further 

 development, or modify them in countless varied ways according 

 to the varying needs of the organism. Whatever other causes 

 have been at work, natural selection is supreme, to an extent which 

 even Darwin himself hesitated to claim for it. The more we study 

 it, the more we are convinced of its overpowering importance, and 

 the more confidently we claim, in Darwm's own words, that it ' has 

 been the most important, but not the exclusive, means of modifica- 

 tion.' 



Now, in the latter quotation it is manifest that the " co-opera- 

 tion " which is spoken of takes cognizance only of factors which 

 are themselves either necessary conditions to, or integral parts of, 

 the process of natural selection ; and, therefore, the approval which 

 Mr. Wallace bestows upon Mr. Darwin's emphatic reservation — 

 "but not exclusive means of modification" — can only be understood 

 to have reference to the development of those distinctively human 

 faculties which he immediately proceeds to consider, and touching 

 which, as already indicated, Mr. Darwin's reservation was certainly 

 not intended to apply. Thus, in brief, at the time of Mr. Darwin's 

 death the state of matters was this : while Mr. Wallace held per- 

 sistently to his original belief in natural selection as virtually the 

 sole and only cause of organic evolution, the whole body of scien- 

 tific opinion, both in this country and abroad, had followed Mr. 

 Darwin in holding that, while natural selection was " the main " 

 factor of such evolution, nevertheless it was largely supplemented 

 in its work by certain other subordinate factors, of which the most 

 important were taken to be the inherited effects of use and disuse, 

 together with the influence of the environment in directly producing 

 alterations both of structure and of instinct. 



Shortly after Mr. Darwin's death, however, this state of matters 

 underwent a very serious change. For it was shortly after Mr. 

 Darwin's death that Professor Weismann began to publish a re- 

 markable series of papers, the effect of which has been to create a 

 new literature of such large and rapidly increasing proportions that, 

 with the single exception of Mr. Darwin's own works, it does not 

 appear that any publications in modern times have given so great 

 a stimulus to speculative science, or succeeded in gaining so in- 

 fluential a following. The primary object of these papers is to 

 establish a new theory of heredity, which has for one of its conse- 

 quences a denial of the inherited effects of use and disuse, or, in- 

 deed, of any other characters which are acquired during the life- 

 time of individuals. According to this theory, the only kind of 

 variations that can be transmitted to progeny are those which are 

 called congenital. 



For instance, there is no doubt that in his individual lifetime the 

 arms of a blacksmith have their muscular power increased by con- 

 stant exercise or use of the muscles in hammering ; and therefore, 

 if there were a thousand generations of blacksmiths, it seems rea- 

 sonable to suppose that the children of the last of them would in- 

 herit somewhat stronger arms than tho.se of average children, — or, 

 a fortiori, than those of children born of a similarly long line, say, 

 of watchmakers. This was the supposition that constituted the 

 basis of Lamarck's theory of evolution, and, as we have seen, it 

 was sanctioned by Darwin : although, of course, he differed from 

 Lamarck in not regarding this supposed transmission of the effects 

 of use and disuse as the sole factor of evolution, but merely as a 

 factor greatly subordinate to that which he had himself discovered 

 in survival of the fittest. Nevertheless, he unquestionably did re- 

 gard this subordinate 'actor as one of high importance in co-opera- 

 tion with survival of the fittest, and, as Mr. Herbert Spencer has 

 shown in detail, he apparently attributed more and more impor- 

 tance to it the longer that he considered its relation to the greater 

 principle. 



But, as we have just seen, according to the school of Weismann 

 it is only variations of a congenital kind that can be inherited. No 

 matter what adaptive changes may be induced in the individual by 

 suitable use and disuse of its several parts, and no matter what 

 adaptive changes may be directly caused by environing agencies, 

 these all count for nothing in the process of evolution. The only 

 adaptive changes that can count for anything in this process are 

 those which can be transmitted to progeny ; i.e., according to this 



