CHAPTER XI 



Wilhelm Roux's Theory 



The organicist view and its distinctive characters. — Importance 

 of external factors. — Exponents of the theory: O. Hertwig, 

 Herbst, J. Loeb, Driesch. — Tropisms and tactisms. — 

 W. Roux and biomechanics. — The theory of "the mosaic"; 

 the struggle between parts of the organism ; functional stim- 

 ulation. — Evidence: the formation of spongy tissue in bones; 

 pseudarthrosis. — A discussion of Roux's theory; its merits. 

 — Its relation to selectionism and Lamarckism. 



THE theory which constitutes the subject-matter 

 of this chapter never developed into any system 

 as elaborate and inclusive as the systems based upon 

 the idea of representative particles. Wilhelm Roux 

 ventures no such surmises and only considers the con- 

 crete organism, its tissues and cells. In his explana- 

 tion of ontogenesis he attaches the utmost importance 

 to external factors and to the activity of the various 

 organs. In that respect, organicism is the perfect 

 antithesis of Weismannism. While the latter theory 

 is related to early evolutionism and to Neo-Darwin- 

 ism, the former has many features in common with 

 the old theory of epigenesis and Lamarckian trans- 

 formism. 



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