becomes "indirect equilibration." The discussion of these two principles is among the most profound of all of Spencer's writings. The subject, so intimately connected with this, of the transmission of acquired characters, was not overlooked in the "Principles of Biology," but it was not brought into the foreground until Weismann's "Essays" began to appear, denying its possibility. Spencer, as is known, entered the lists with his paper on "The Factors of Organic Evolution," and continued to reply to Weismann for a number of years. In him the trained biological specialist found a foeman worthy of his steel. Headers of these papers on both sides will of course differ in their judgments on the argument according to their cast of mind, but all will admit that Spencer's presentation of the case was able, and to it, as much as to anything else, were due the many notable concessions that Weismann was from time to time compelled to make.[1]
In the second volume of the "Principles of Biology," devoted mainly to morphology and physiology, Spencer showed that he could play the rôle of a specialist, but his special studies and illustrations all have a philosophic purpose in establishing principles. These, however, belong for the most part to the minor or more special laws of biology, and do not call out the same philosophic powers as the major and more general laws dealt with in the first volume. Perhaps the most important of these laws is what he calls the "antagonism between growth and sexual genesis," which might otherwise be stated as the law that nutrition and reproduction are inversely proportional. The truth of this is known to practical breeders, florists and horticulturists, but not to the general public, and it has some interesting results.
Spencer lived to revise his "Biology" and introduce into it much of the Weismann controversy and other features which had not presented themselves clearly at the time the work was originally written. Upon the whole it is a remarkable work. Surprise has often been expressed that trained specialists in biology had rarely or never been able to trip him on any of his statements. This is partly explainable by the fact that Professor Huxley read the proof of a considerable part of the work, but it does not appear that he found much to correct, and we must admit that Spencer possessed a remarkable faculty of accurately stating biological facts that he had not himself observed, and a still greater talent for correlating and interpreting them and fitting them into his universal scheme.
Let us now turn to the "Principles of Psychology." In his "Synthetic Philosophy" Spencer placed it after the Principles of Biology. Although he says little about his reasons for this arrangement, it seems clear that he regarded it as the order of evolution. Yet
- ↑ Cf. Weismann's "Concessions," Popular Science Monthly, Vol. XLV., June, 1894, pp. 175-184.
