Introduction 



.HE PURPOSE OF THE SYMPOSIUM on wliich this book is based was to pre- 

 sent, by means of a series of papers dealing with representative problems, 

 a cross-section of contemporary research on temperature relations of bio- 

 logical processes at various levels of complexity, extending from the purely 

 molecular, up tlu'ough cells, tissues and organs, to whole organisms. In the 

 light of present knowledge it was considered appropriate to include, as an 

 aspect of the same subject, papers dealing primarily with the action of 

 hydrostatic pressure. From several points of view, a symposium embody- 

 ing both of these aspects may be considered a timely one. 



The timeliness of the symposium, and the appropriateness of including 

 papers on hydrostatic pressure, cannot be fully appreciated without ref- 

 erence to the general background as well as to the present status of re- 

 search in this broad and fundamental area. More than passing comment, 

 therefore, is called for concerning the manner in which studies on the 

 biological effects of temperature and pressure began and progressed, as 

 well as the advances that brought these seemingly unrelated fields of 

 endeavor together, and the potential usefulness of such studies as avenues 

 of approach to the understanding of basic mechanisms involved in the 

 control of physiological processes. 



With the advent of the Arrhenius theory of chemical reaction rates, 

 in 1889,^ a theoretical basis became available for interpreting biological 

 rates in terms of laws applicable to ordinary chemical reactions. Various 

 enzyme reactions in solution, as well as more complex processes in living 

 cells, were soon found to conform in some measure to the Arrhenius equa- 

 tion; frequently, within certain ranges of temperature below the 'optimum' 

 of a given process, the log of the rate turned out to be a linear function of 

 the reciprocal of the absolute temperature. At temperatures only slightly 

 above the optimum, the rate of thermal destruction in many instances also 

 conformed to the Arrhenius equation. At intermediate temperatures, how- 

 ever, more complicated functions were encountered. Although these com- 

 plications became the subject of much discussion and some interesting 

 ideas, no convincing, quantitative theory to explain them emerged. 



^ References to the literature cited in this preface may be found in a recent book, 

 The Kinetic Basis of Moleculnr Biology, by Johnson, Eyring and PoHssar (Wiley, 

 New York, 1954), which treats the biological effects of temperature and pressure from 

 the point of view of modern reaction rate theory. 



IX 



