Modern philanthropy--so far at least as it ever studies ultimate results--constantly relies on this ill-founded belief as its justification for ignoring the warnings of those who point out the ultimately disastrous results of a systematic defiance or reversal of the great law of natural selection. This reliance finds strong support in Mr. Spencer's latest teachings, for he holds that the inheritance of the effects of use and disuse takes place universally, and that it is now "the chief factor" in the evolution of civilized man (pp. 35, 74, iv)--natural selection being quite inadequate for the work of progressive modification. Practically he abandons the hope of evolution by natural selection, and substitutes the ideal of a nation being "modified _en masse_ by transmission of the effects" of its institutions and habits. Use-inheritance will "mould its members far more rapidly and comprehensively" than can be effected by the survival of the fittest alone. But could we rely upon the aid of use-inheritance if it really were a universal law and not a mere simulation of one? Let us consider some of the features of this alleged factor of evolution, seeing that it is henceforth to be our principal means of securing the improvement of our species and our continued adaptation to the changing conditions of a progressive civilization. It is curiously uncertain and irregular in its action. It diminishes or abolishes some structures (such as jaws or eyes) without correspondingly diminishing or abolishing other equally disused and closely related parts (such as teeth, or eye-stalks). It thickens ducks' leg-bones while allowing them to shorten. It shortens the disused wing-bones of ducks and the leg-bones of rabbits while allowing them to thicken; and yet in other cases it greatly reduces the thickness of bones without shortening them. It transmits tameness most powerfully in an animal which usually cannot acquire it. It aids in webbing the feet of water-dogs, but fails to web the feet of the water-hen or to remove the web in the feet of upland geese.[72] It allows the disused fibula to retain a potentiality of development fully equal to that possessed by the long-used tibia. It lengthens legs because they are used in supporting the body, and shortens arms because they are used in pulling. Whether it enlarges brain if used in one way and diminishes it if used in another, we cannot tell; but it must obviously deaden nervous sensibilities in some cases and intensify them in others. It enlarges hands long before they are used, and thickens soles long before the time for walking on them. At the same time, as if by an oversight, it so delays its transmission of the habit of walking on these thickened soles, that the gradual and tedious acquisition of the non-transmitted habit costs the infant much time and trouble and often some pain and danger. Yet where aided by natural selection, as with chickens and foals, it transmits the habit in