PKEFACE 



I SHOULD not have had the courage to offer these 

 volumes to the public, had not requests repeatedly come to 

 me from physicians and biologists to render my publications, 

 which are widely scattered, more easily accessible. There- 

 fore, when the editor of the "Decennial Publications of the 

 University of Chicago" invited me to make a contribution 

 to the series, I mentioned to him, not without hesitation, 

 the idea of collecting and republishing my papers on 

 General Physiology. Through his initiative and kind as- 

 sistance the idea has been carried out. 



No one will expect that a collection of papers on very 

 diverse subjects can form attractive reading matter. Yet I 

 may mention, by way of an apology, that, in spite of the 

 diversity of topics, a single leading idea permeates all the 

 papers of this collection, namely, that it is possible to get 

 the life-phenomena under our control, and that such a control 

 and nothing else is the aim of biology. Thus the reader 

 will notice that in a series of these publications I have tried 

 to find the agencies which determine unequivocally the 

 direction of the motion of animals, and he will also notice 

 that I consider a complete knowledge and control of these 

 agencies the biological solution of the metaphysical problem 

 of animal instinct and will. In taking up the problem of 

 regeneration I started out with the idea of controlling these 

 phenomena, and considered it my first aim to find means by 

 which one organ could at desire be caused to grow in the place 

 of another organ. Thus the experiments on heteromorphosis 

 originated. , As far as the problem of fertilization is con- 

 cerned, it seemed to me that the first step toward its solution 

 should consist in the attempt to produce larvse artificially 

 from unfertilized eggs in various classes of animals. 



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852 



