CHAPTER XVIII 



MODERN THEORETICAL SPECULATIONS 



I. Mechanism and Vitalism 



IT WILL HAVE BEEN SEEN from the previous chapter that biology in our 

 own day has distinguished itself far more through practical detailed re- 

 search than through theoretical speculations. Actually no further gen- 

 erally accepted theory of life such as that offered by Darwinism has been 

 discovered; instead, there has prevailed, a restless search for fresh grounds 

 on which a theory of life might be built up. Many have been the roads along 

 which the search for the theoretical solution of the problem of life has been 

 made since the turn of the century, and they have run in widely differing 

 directions. On the one hand, we find repetitions in a newer form of the old 

 materialistic and mechanistic theories of life from the days of Vogt and 

 Haeckel; on the other hand, vitalistic ideas that have looked for support 

 in Bichat, in Stahl, in Aristotle. The old antagonism, Christian conservatism 

 versus Darwinistic radicalism, which half a century ago resulted in the for- 

 mation of parties, has now been essentially adjusted, though in no wise 

 everywhere eradicated; in this respect it must be acknowledged that the 

 struggle in modern times is more definitely a matter of facts than it was 

 previously, at least among students, but the differences of opinion have in 

 many quarters certainly been sharp enough. It is possible to give here only 

 a few examples of views taken from the rival camps, this as a final summary 

 of the position of biology as it stands in the present generation; unfortunately 

 it is more difficult than ever to draw conclusions from them as to the direc- 

 tion likely to be taken by evolution in the future. 



Max Verworn (1861-19x1) was born in Berlin, studied there and at 

 Jena, and eventually became professor of physiology at Gottingen. He was 

 a pupil of Haeckel and throughout his life retained both his admiration for 

 his master and his association with Haeckel's fundamental ideas. To him 

 the biogenetical principle as well as the theory of selection always was a 

 proved fact; of the more recent contributions to the hypothesis of evolution 

 he embraced de Vries's mutation theory, but he showed no interest in Men- 

 delism. On these foundations, however, he built up a life theory of his own 



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