Its Physical Basis and Definition BY JOHN BUTLER BURKE NEW YORK FREDERICK A. STOKES COMPANY PUBLISHERS PREFACE IN presenting this work to the judgment of my critics, as the result in part of my studies for some years past, in some respects in outline whilst in others in detail, and more so perhaps than it was my intention at first to make it, two points should be borne in mind. In the first place, it is intended that the chapters which deal with phosphorescence may with advantage be omitted by those who are not particularly interested in such matters, since they may tend to divert the attention from the real points at issue, if the mind is not specially familiar with physical conceptions. The reader who does not wish to be burdened with detail is therefore recommended to omit them, at any rate on the first reading, if the book should prove of sufficient interest to demand his perusal for a second time. Those chapters of a purely physical and perhaps somewhat technical nature, which he thus may think it worth his while to pass over, have been introduced to illustrate the way in which the phenomenon which I have called physical metabolism admits of comparison with the highly |