VII. NEW BOOKS.

[These Notes (by various hands) do not exclude Critical Notices later on.] The Factors of Organic Evolution. By HERBERT SPENCER. Reprinted, with additions, from The Nineteenth Century. London : Williams and Norgate, 1887. Pp. iv., 76. " Though the direct bearings of the arguments contained in this Essay," Mr. Spencer says, "are biological, the argument contained in its first half has indirect bearings upon Psychology, Ethics, and Sociology. My belief in the profound importance of these indirect bearings, was originally a chief prompter to set forth the argument, and it now prompts me to reissue it in permanent form." In the first half, after describing his original acceptance of the Lamarckian doctrine of evolution, and the enlarged view of the factors of evolution that was the consequence of the publication of the Origin of Species, he goes on to ask whether the process brought into view by Darwin, taken alone, accounts for organic evolution, as is now supposed by many naturalists. The answer is that " utterly inadequate to explain the major part of the facts as is the hypothesis of the inheritance of functionally-produced modifications, yet there is a minor part of the facts, very extensive though less, which must be ascribed to this cause". Darwin himself came to recognise this more and more, and there are reasons for thinking that the reaction displayed in his later writings ought to be carried further. But if, "along with inheritance of useful variations fortuitously arising, there has been inheritance of effects produced by use and disuse ; do there remain no classes of organic phenomena unaccounted for ? " To show that there is still another factor of organic evolution is the object of the second half of the Essay. This third factor is that which is so prominent in the Principles of Biology, viz., the direct action of the inorganic environment. Both inductively and deductively this direct action is found to be " the primordial factor of organic evolution ". As a name for that effect of external causes which depends on a struggle among organisms, Mr. Spencer's own term " survival of the fittest," as well as "natural selection" "calls up an anthropocentric idea" (p. 41). For the purpose of ascertaining their causes, organic pheno- mena should be contemplated simply as "groups of changes". Human ideas of "fitness" and "unfitness" are then seen to be inapplicable, and it is recognised that natural selection "could do no more than take advantage of those structural changes which the medium and its contents initiated ". What then are the relations of the three factors 1 This is the subject of a speculation at the end of the Essay (pp. 72-5) by which the view Mr. Spencer had formerly arrived at, viz., that natural selection is most im- portant in the earliest stages of evolution, " direct adaptation " in the later (see, for example, Biology, 170) is made more precise. Three stages are now recognised, in the first of which the most important factor is that which has been called primordial, in the second " natural selection," in the third "functional adaptation". The stage in which functional adaptation, constantly rising in importance as activity and complexity of life increase, becomes the chief factor, has been reached by civilised men, among whom such aid as survival of the fittest gives is " usually limited to the preserva- tion of those in whom the totality of the faculties has been most favourably