PREFACE 
I sHoutp 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 larve artificially 
from unfertilized eggs in various classes of animals. 
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