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points of view, helped to reconstruct and readjust our ideas of the relations of 

 embryological processes, and hence of the phenomenon of life itself, on the one 

 hand to physical causes (whether external to or latent in the mechanism of the 

 cell), or on the other to the ancient conception of a Vital Element alien to the 

 province of the physicist. 



No small number of theories or hypotheses, that seemed for a time to have 

 been established on ground as firm as that on which we tread, have been reopened 

 in our day. The adequacy of natural selection to explain the whole of organic 

 evolution has been assailed on many sides ; the old fundamental subject of 

 embryological debate between the evolutionists or preformationists (of the 

 school of Malpighi, Haller, and Bonnet) and the advocates of epigenesis (the 

 followers of Aristotle, of Harvey, of Caspar F. Wolff, and of Von Baer) is now 

 discussed again, in altered language, but as a pressing question of the hour; the 

 very foundations of the. cell-theory have been scrutinised to decide (for instance) 

 whether the segmented ovum, or even the complete organism, be a colony of 

 quasi-independent cells, or a living unit in which cell differentiation is little 

 more than a superficial phenomenon ; the whole meaning, bearing, and philosophy 

 of evolution has been discussed by Bergson on a plane to which neither Darwin 

 nor Spencer ever attained ; and the hypothesis of a Vital Principle, or vital 

 element, that had lain in the background for near a hundred years, has come into 

 men's mouths as a very real and urgent question, the greatest question for the 

 biologist of all. 



In all ages the mystery of organic form, the mystery of growth and reproduc- 

 tion, the mystery of thought and consciousness, the whole mystery of the 

 complex phenomena of life, have seemed to the vast majority of men to call 

 for description and explanation in terms alien to the language which we apply 

 to inanimate things; though at all times there have been a few who sought, 

 with the materialism of Democritus, Lucretius, or Giordano Bruno, to attribute 

 most, or even all, of these phenomena to the category of physical causation. 



For the first scientific exposition of Vitalism we must go back to Aristotle, 

 and to his doctrine of the three parts of the tripartite Soul : according to which 

 doctrine, in Milton's language, created things ' by gradual change sublimed, To 

 vital spirits* aspire, to animal, To intellectual ! ' The first and lowest of these 

 three, the ^/vxh V BpcrrtKy, by whose agency nutrition is effected, is y irpdry 

 tyvxk, the inseparable concomitant of Life itself. It is inherent in the plant as 

 well as in the animal, and in the Linnsean aphorism, Vegetabilia crescunt et 

 vivunt, its existence is admitted in a word. Under other aspects it is all but 

 identical with the ifivxh av|r)Ti/d7 and yevr)Tiiii\, the soul of growth and of repro- 

 duction : and in this composite sense it is no other than Driesch's ' Entelechy/ 

 the hypothetic natural agency that presides over the form and formation of 

 the body. Just as Driesch's psychoid or psychoids, which are the basis of 

 instinctive phenomena, of sensation, instinct, thought, reason, and all that 

 directs that body which entelechy has formed, are no other than the alcrdyTtK-fi, 

 whereby animalia vivunt et scntiunt, and the Hiavonriie-ii, to which Aristotle 

 ascribes the reasoning faculty of man. Save only that Driesch, like Darwin, 

 would deny the restriction of vovs, or reasoning, to man alone, and would extend 

 it to animals, it is clear, and Driesch himself admits, 1 that he accepts both the 

 vitalism and the analysis of vitalism laid down by Aristotle. 



The Trvevfxa of Galen, the vis plastica, the vis vita, formatrix, of the older 

 physiologists, the Bildungstrieb of Blumenbach, the Lebenskraft of Paracelsus, 

 Stahl, and Treviranus, ' shaping the physical forces of the body to its own ends,' 

 ' dreaming dimly in the grain of the promise of the full corn in the ear,' 2 these 

 and many more, like Driesch's ' entelechy ' of to-day, are all conceptions under 

 which successive generations strive to depict the something that separates the 

 earthy from the living, the living from the dead. And John Hunter described 



1 Science and Philosophy of the Organism (Gifford Lectures), ii., p. 83, 1908. 



a Cit. Jenkinson (Art. 'Vitalism' in Hibbert Journal, April 1911), who has 

 given me the following quotation : ' Das Weitzenkorn hat allerdings Bewusstsein 

 dessen was in ihm ist und aus ihm werden kann, und traumt wirklich davon. 

 Sein Bewusstsein und seine Traume mogen dunkel genug sein ' ; Treviranus, 

 Erscheinungen und Gesetze des organischen Lebens, 1831. 



