Further on, following Radl, he characterises Darwin's attitude to the law of correlation in these terms:--"Darwin's interest is entirely focussed on the variation, the function, the causes of form-production, in short, upon evolution. Accordingly he regards correlation essentially as correlative variation in the sense of a _departure_ from the given type. With morphological correlation in _different_ types Darwin troubles himself not at all, nor with correlation in the normal development of a type" (p. 49). Cuvier's conception of the _convenance des parties_, essential to all biology, remained on the whole foreign to Darwin's thought, and to the thought of his successors. It was indeed one of their boasts that they had finally eliminated all teleology from Nature. The great and immediate success which Darwinism had among the younger generation of biologists and among scientific men in general was due in large part to the fact that it fitted in well with the prevailing materialism of the day, and gave solid ground for the hope that in time a complete mechanistic explanation of life would be forthcoming. "Darwinismus" became the battle-cry of the militant spirits of that time. It was precisely this element in Darwinism that was repugnant to most of Darwin's opponents, in whose ranks were found the majority of the morphologists of the old school. They found it impossible to believe that evolution could have come about by fortuitous variation and fortuitous selection; they objected to Darwin that he had enunciated no real _Entwickelungsgesetz_, or law governing evolution. They were not unwilling to believe that evolution was a real process, though many drew the line at the derivation of man from apes, but they felt that if evolution had really taken place, it must have been under the guidance of some principle of development, that there must have been manifested in evolution some definite and orderly tendency towards perfection.[360]