SCIENCE 



Friday, November 12, 1920 



CONTENTS 



The Proteins mid Colloid Chemistry: Dr. 

 Jacques Loeb 449 



The African Rift Valleys: Professor "W. M. 

 Davis 456 



Scientific Events: — • 

 The Sixteenth Annual New England Inter- 

 collegiate Geological Excursion; "Physio- 

 logical Reviews;" University of Pennsyl- 

 vania Lectures; The Section of Zoology of 

 the American Association 458 



Scientific Notes and News 461 



University and Educational News 464 



Discussion and Correspondence: — 



The Preservation of Wild Life: Professor 

 V. B. Shelford. Predilection and Sampling 

 of Human Heights: Professor Edwin G. 

 Boring. The Plight of Scientific Period- 

 icals: Dr. Howard S. Eeed. Boad Reflec- 

 tions: H. H. Platt. The Influence of Fresh 

 Food in Lactation: E. B. Eorbes. Swarm- 

 ing of Anopheles : Dr. L. O. Howard 465 



The WorTcs of Ameghino: Professor Koy L. 

 MooDiE ^ 469 



Special Articles: — 



The Free Martin and its Reciprocal; Opos- 

 sum, Man, Dog: Professor Carl G. Hart- 

 man 469 



The Nebraslca Academy of Sciences: C. O. 

 Carlson 471 



MSS. intended for publication and books, etc., intended for 

 review should be sent to The Editor of Science, Garrison-on- 

 Hudson, N. Y. 



THE PROTEINS AND COLLOID 



CHEMISTRYi 



I 



The proteins, like certain other constituents 

 of protoplasm, are colloidal in character, i. e., 

 they are not able to diffuse through animal 

 membranes which are permeable to crystal-' 

 loids. For this reason a number of authors 

 have tried to explain the behavior of proteins 

 from the viewpoint of the newer concepts of 

 colloid chemistry. Foremost among these 

 concepts is the idea that the reactions be- 

 tween colloids and other bodies are not deter- 

 mined by the purely chemical forces of 

 primary or secondary valency but follow the 

 rules of " adsorption." Although a number 

 of authors, during the last twenty years, e. g., 

 Bugarszky and Liebermann, Hardy, Pauli, 

 Robertson, Sorensen, and others, have advo- 

 cated a chemical conception of the reactions 

 of proteins, their experiments failed to con- 

 vince the other side since these experiments 

 could just as well be explained on the basis 

 of the adsorption theory. There were two 

 reasons for this failure. First, the experi- 

 ments did not show that ions combined with 

 proteins in the typical ratio in which the 

 same ions combine with crystalloids. This 

 proof only became possible when it was 

 recognized that the hydrogen ion concentra- 

 tion of the -protein solution determines the 

 amount of ion entering into combination 

 with a protein, and that therefore the ratios 

 in which different ions combine with proteins 

 must be compared for the same hydrogen ion 

 concentrations. Since the former workers 

 were in the habit of comparing the effects of 



1 Address delivered before the Harvey Society, 

 October 16, 1920. The writer's experiments, on 

 which this address is based, have appeared in the 

 J. Gen. Physiol, 1918-19, I., 39, 237, 363, 483, 

 559; 1919-20, II., 87; 1920-21, III., 85. 



