PREFACE 



"//, therefore, anyone wishes to search out the truth of 

 things in serious earnest, he ought not to select one special 

 science; for all the sciences are conjoined with each other and 

 interdependent . ' ' 



Thus wrote the French philosopher Rene Descartes. The 

 purpose of this book is to show the truth of this statement in 

 the study of protoplasm. On the pages that follow are brought 

 together all those parts of the branches of science which bear 

 upon the physical chemistry of living matter. Obviously, 

 there is a space limit to what can be told, but at least enough 

 will be said to indicate how far research has gone in the applica- 

 tion of physics and chemistry to those biological phenomena 

 which can be reduced to cellular or protoplasmic processes. 



The presentation is as nontechnical as is consistent with 

 accuracy and completeness. Mathematical formulas, curves, 

 and tables have not been omitted — it would be difficult to do 

 so in a number of instances where the subject defies a wholly 

 nontechnical presentation — but they have been resorted to as 

 infrequently as possible. A mathematical formula or a graph 

 may, at first sight, be somewhat awe-inspiring, yet it often 

 presents a complex situation in a simple and intelligible manner. 

 On the other hand, it is equally true that a situation which can 

 be clearly put into words becomes meaningless to the non- 

 mathematical mind when stated in terms of formulas and curves. 



The readers for whom this book has been written are students 

 in biology and medicine and the related fields of biophysics and 

 biochemistry. While it is not intended for my colleagues, should 

 this volume fall into their hands, I trust they will find it of interest. 



A list of references is appended, in case the reader should care 

 to delve more deeply into the subject of this or that chapter. 



Every effort has been made to present both sides of a question, 

 yet with emphasis on that side which is favored by the author, 

 in the belief that a definite but not too arbitrary stand is more 

 conducive to the clear grasp of a subject than a wholly impartial 

 point of view. With opposing evidence presented, the reader 

 can judge for himself. A book wholly devoid of contention is 

 likely to be less stimulating than one which occasionally indulges 

 in healthy disagreement. A sincere attempt has, however, 



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