INTRODUCTION 



SEVEN OF THE NINE CONTRIBUTIONS to this monograph were presented in 

 jiart at a Symposium on "Electrolytes in Biological Systems", organized 

 by Abraham M. Shanes at the request of the Society of General Physiologists, 

 at the Society's ninth annual meeting held at the Marine Biological Laboratory, 

 Woods Hole, Massachusetts, on September 8, 1954. The organizing chairman 

 was also asked to look into the possibility of publication, which led to the pres- 

 ent volume. Two additional sections — on the higher plants by Dr. Epstein 

 and on chloride transfer by Dr. Hogben — which could not be presented at the 

 Symposium, have been included to broaden the scope of the volume. 



The Symposium and the monograph are dedicated to two investigators — Dr. 

 M. H. Jacobs and Dr. W. J. V. Osterhout — whose extensive work and thought 

 in this field have provided a broad base for current methods and concepts and 

 indeed keynote the papers which follow. A foremost feature of their studies has 

 been the extensive use of comparative physiology. They have thus amply dem- 

 onstrated how the similarities and differences among organisms can distinguish 

 the special from the general, the superficial from the basic. The variety of or- 

 ganisms represented by this monograph again demonstrates the value of com- 

 parative studies. The recent tendency to emphasize the sodium ion in several 

 biological systems as a result of the recent excellent work on frog skin is seen to 

 require careful evaluation in the light of the present evidence for discrete mech- 

 anisms for chloride movement in gastric mucosa and for sodium and potassium 

 transfer m Ulva, Valonia and nerve. The demonstration by Cowie and Roberts 

 of the marked permeability of E. coli and other microorganisms to solutes 

 known to penetrate cells with difficulty, associated with an ability to retain 

 components to which they are permeable, calls attention to the possibility of 

 mechanisms other than peripheral cell boundaries whereby intracellular com- 

 ponents are controlled. The ion selectivity of mitochondria, described by 

 ]\Iudge, represents one property susceptible of study which offers considerable 

 promise for an understanding of the role of protoplasmic constituents in the 

 regulation of the intracellular environment. 



The comparative viewpoint is of considerable value in permitting selection 

 of material particularly suitable for the elucidation of specific principles. This is 

 evident in research such as that by Rothstein and Epstein which has been re- 

 markably successful in revealing the importance of surface reactions in the 

 penetration of substances into organisms. 



