It is instructive to notice that Darwinism seems likely to be robbed of its stock illustration, namely, “protective coloration.” By its own internal power of reaction, and sometimes within one generation, and even in the lifetime of an individual, an organism may assume the colour of the substratum beneath it (soles, grasshoppers), of its surroundings (Eimer’s tree frogs), the colour and spottiness of the granite rock on which it hangs, the colour of the leaves and twigs among which it lives (Poulton’s butterfly pupæ), and even that of the brightly coloured sheets of paper amidst which it is kept imprisoned. Certain spiders assume a white, pink, or greenish “protective coloration” corresponding to the tinted blossom of the plants which they frequent, and so on.(51) Eimer alleged that direct psychical factors co-operated in bringing about these changes. In any case, all this carries us far beyond the domain of mere naturalistic factors into the mystery of life itself. Even what is called the “influence of the external world,” and the “active acquirement of new characters,” have their basis and the reason of their possibility in this domain. And the whole domain is saturated through and through with “teleology.” A recognition of the impressive secret of the organism led Gustav Wolff to become a very pronounced critic of Darwinism, especially in the form of Weismannism. As far back as 1896, in a lecture “On the present position of Darwinism,” in which he dealt only with Weismann, he criticised and analysed that author’s last attempt to uphold Darwinism by the construction of his theory of “germinal selection.” He concluded with the wish: “That a spirit of earnestness would once more enter into biological investigation, which would no longer attempt to find in nature just what it wanted to find, but would be ready to follow truth at all costs, and to approach the riddle of life with an open mind.”