Nature, therefore, while doing in the case of these insect communities exactly what she appears to be doing elsewhere by the accumulation of acquired characteristics, must, in reality, have been working on entirely different lines. If we can discover what those lines were, they will cover the apparently Lamarckian cases as well, but the Lamarckian principle certainly will not cover these.
In the next chapter we shall review the alternative explanation offered by Darwinism, the explanation of Weismann; and we shall see whether Spencer was not as successful in demolishing it as Weismann was in showing that, if evolution exists at all, some other basis must be found for it than that on which it was so largely rested by Herbert Spencer.
CHAPTER V
THE MECHANICAL THEORY OF EVOLUTION: THE DARWIN-WEISMANN EXPLANATION
“Chance guides all things: mind and forethought must call it God alone!”—Menander.
“IN the end,” writes M. Edmond Perrier, “every imaginable theory of evolution must lead up to one or other of two absolute doctrines, essentially antagonistic to each other. Either the inheritance of acquired characteristics must be admitted in its full scope (dans toute sa généralité), or else we must believe in the predestination of protoplasm, developing by virtue of its own internal forces. But in the latter case we pass from the domain of pure science to enter that of metaphysics.”[66]
We have now to consider the most conspicuous attempt made in recent times to escape from this tragic dilemma.