PREFACE 



The present volume is based in part on lectures 

 delivered in Clark University and the Marine Biological 

 Laboratory, on the physico-chemical basis of the more 

 general or fundamental properties of living matter. 

 Common to all forms of living matter are certain proper- 

 ties or modes of action which are absent or imperfectly 

 developed in non-living matter. The chief of these are 

 (i) the property of specific growth, and (2) a unification 

 or integration of activities, of such a kind as to secure the 

 continued existence of the living system in its environ- 

 ment. The question of how the living system must be 

 constituted (in the physico-chemical sense) in order to 

 exhibit such properties is the fundamental one for 

 physiology. 



Of late years the analytical investigation of the 

 living organism and its products has made great advances; 

 on the synthetic side, however, progress has been 

 relatively shght. The precise manner in which certain 

 special physico-chemical materials and processes are 

 combined so as to produce life still remains largely 

 obscure. It may be expected that properly directed 

 experiment will throw light on this problem, as it has 

 on many others apparently equally difficult, but at 

 present we are at a stage where exact or scientific knowl- 

 edge is only in its beginning. 



In this book I have made no attempt to consider in 

 detail the many special problems of pure physics and 

 chemistry which are presented by the organism. It is 



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