Of course, the advance of science began to make rapid progress. The solution of one problem always brings a few more problems to the surface to be solved, which were hidden underneath the theory of transmission that Darwin had to accept as a basis of inquiry was ever more investigated, a hot discussion arose about the individual factors of development and the struggle for existence. While a few scientists directed their attention to variation, which they considered due to exercise and adaptation to life (following the principle laid down by Lamarck) this idea was expressly denied by scientists like Weissman and others. While Darwin only assumed gradual and slow changes, De Vries found sudden and leaping cases of variation resulting in the sudden appearance of new species. All this, while it went to strengthen and develop the theory of descent, in some cases made the impression that the new discoveries rent asunder the Darwinian theory, and therefore every new discovery that made it appear so was hailed by the reactionists as a bankruptcy of Darwinism. This social conception had its influence on science. Reactionary scientists claimed that a spiritual element is necessary. The supernatural and insolvable has taken the place of Darwinism and that class which in the beginning was the banner bearer of Darwinism became ever more reactionary. V. DARWINISM VERSUS SOCIALISM. Darwinism has been of inestimable service to the bourgeoisie in its struggle against the old powers. It was therefore only natural that bourgeoisdom should apply it against its later enemy, the proletarians; not because the proletarians were antagonistically disposed to Darwinism, but just the reverse. As soon as Darwinism made its appearance, the proletarian vanguard, the Socialists, hailed the Darwinian theory, because in Darwinism they saw a corroboration and completion of their own theory; not as some superficial opponents believe, that they wanted to base Socialism upon Darwinism but in the sense that the Darwinian discovery,――that even in the apparently stagnant organic world there is a continuous development――is a glorious corroboration and completion of the Marxian theory of social development. Yet it was natural for the bourgeoisie to make use of Darwinism against the proletarians. The bourgeoisie had to contend with two armies, and the reactionary classes know this full well. When the bourgeoisie attacks their authority, they point at the proletarians and caution the bourgeoisie to beware lest all authority crumble. In doing this, the reactionists mean to frighten the bourgeoisie so that they may desist from any revolutionary activity. Of course, the bourgeois representatives answer that there is nothing to fear; that their science but refutes the groundless authority of the nobility and supports them in their struggle against enemies of order.