THE POPULAR SCIENCE MONTHLY.
the development of scientific thought, I am aiming only to show, as can so easily be shown, and as simple justice requires to be shown, that it is altogether an exaggeration to speak of him as the father of the modern doctrine of evolution. What Darwin did was to amass an enormous number of facts from almost every department of biological science, and by the devoted labor, patient examination, and long-searching thought of many studious years, to establish, once and for all, not the reality of evolution, nor even the laws and conditions of evolution, but the operation of one of the main factors of evolution — a factor which, though it had till his time entirely eluded the scientific mind, was yet required to render comprehensible a vast array of phenomena otherwise without interpretation. How near Mr. Spencer's own investigations had led him to a realization of the process of natural selection, or, as he afterward called it, the survival of the fittest in the struggle for existence, we have already been able to remark, and he himself took occasion to point out, when in the course of his later work he came to deal more systematically with the whole problem of animal fertility and its practical implications. But the factors mainly relied upon by him, in common with all pre-Darwinian developmentalists, were the direct action of the environment and the inheritance, with increase, of functionally-produced modifications; and as these processes, whatever might be their individual importance (and this is probably somewhat underrated by scientists of the present day), were obviously incapable of throwing light upon a large part — perhaps the larger part — of the facts which pressed for explanation, the theory of evolution could not for the time being hope for inductive establishment. Darwin's book put the whole question upon a new foundation, by exhibiting a process which did account for the hitherto unmanageable facts; and undoubtedly it was thus to a large extent effectual in bringing the general theory into open court as an entertainable hypothesis. But while all this is freely conceded — while the greatness of Darwin's work in itself, and its importance as a contribution to scientific thought, are acknowledged without hesitation, it has still to be remembered that that work was special and limited in character, and that with the general doctrine of evolution at large it had itself nothing whatever to do. The laws of evolution as a univer-
- See Principles of Biology, vol. ii, p. 500, note. The whole of this very interesting note should be studied carefully, not only because it makes clear the scientific relations of Spencer and Darwin, but also for the foreshadowing which it contains of a reaction against that exclusive recognition of natural selection which soon became typical of biological students at large. In his little work, recently published, on The Factors of Organic Evolution, Mr. Spencer has opened the whole question up afresh, by showing that, to obtain a full view of the methods of evolution, other processes besides natural selection have to be taken into account.