By giving to this elemental directive factor the name "entelechy" and by applying to it in its formative aspect the further name "psychoid," Driesch implies and indeed repeatedly affirms not only its reality, but its analogy with what we call the psychical.
Näageli's "Vervollkomnungsprinzip," or inherent factor tending towards progress in evolution, Noll's "Morphæsthesia," or feeling for form which plants are said to possess, Korschinsky's "special tendency to advance," Cope's "archæsthetism," "the inherent driving force," "the inner law of development," "the inner directive force," of other biologists,[2] all have a strangely psychological sound. It is of course true that these positions are vigorously contested by biologists of the orthodox schools, who speak of the "recrudescence" of vitalism. But protests such as the above against the sufficiency of mechanical laws to account for progress in evolution are becoming so many and from such high sources that no psychologist who would postulate a psychic factor of progress, constituting, it may be, the soul of plants, animals and man, need any longer hesitate for fear of censure from the biological camp.
But if vitalism is objectionable, it should be remembered that the choice is by no means between that and the sufficiency of the Darwinian theory of chance variation and natural selection. The number of biologists who accept neither of these solutions of the evolutionary problem is of course very great. If one accepts, for instance, the mutation theory of de Vries, it should be remembered that the difficulties of explaining the cause of the adaptive variations upon which Darwinism depends are greatly increased in explaining the cause of the sudden and rapid mutations in the system of de Vries. In general one may say that the belief in orthogenesis, or development in certain definite directions, has to a considerable extent superseded Darwin's theory of development, and with the increasing belief in orthogenesis comes an increasing demand for some yet unknown factor determining the direction of development, and while there are many theories proposed to account for such development without the introduction of any teleological or psychic factor, nevertheless it appears that those who wish to renew the time-honored hypothesis of some such factor are now heard with increasing respect.
From facts such as these we see not only that many workers in science are busily engaged in the search for the soul, but also that the prospects are reasonably good that they will find it.
But let us return to the psychologists. Another aspect of the tend-
