PROTEINS 491 



tioned. As for the importance of the hydrogen ion, Loeb was 

 right in caUing attention to its dominating influence, but as 

 Kruyt says, while the hydrogen and hydroxyl ions have quantita- 

 tively special functions, other ions play an important role. It is, 

 therefore, a complete misrepresentation of the true relationships 

 to consider that, in contrast to all other ions, the hydrogen ion 

 plays an all-determining part. Kruyt's statement is particularly 

 true for higher concentrations. It is now generally conceded 

 that the hydrogen ion plays a dominant role when all ions are in 

 dilute concentration but that at higher concentrations other ions 

 play an equally significant part. 



IN THE LIVING WORLD 



Wolfgang Pauh, in his book "The Colloid Chemistry of the 

 Proteins," says: 



There can be no doubt as to the central position of the proteins in 

 the organization of living matter. They alone display the specific 

 properties of life. Distinctions observed, not only between different 

 kinds of organisms but often between individuals of the same kind, 

 reappear on chemical investigation as variations in the respective pro- 

 teins. The proteins are capable of showing a diversity and fine grada- 

 tion both in chemical structure and in physical modification to an 

 extent which is lacking in any other class of substances. 



The foregoing statement finds reflection in the work of Wrinch, 

 who has put forward a model of a chromosome as an aggregate of 

 polypeptide protamine molecules in association with nucleic 

 acid. As the number of ionized groups possessed by a nucleic 

 acid molecule varies with pH, the chromosome micelles, or 

 protamine nucleate aggregates, will be capable of different con- 

 figurations for different pH values 



From time to time, emphasis is laid anew on substances other 

 than the proteins as the most fundamental of protoplasmic 

 constituents. Thus, the fact that chromosomes consist in large 

 measure of nucleic acid tends to indicate that this substance is a 

 very significant one in life. The chief rivals of the proteins for 

 first place among the constituents of protoplasm (aside from 

 water) are the fats and fatlike substances such as the sterols and 

 the phosphatides (the so-called lipoids). While the fats do play 

 an important role in vital processes, they seem to serve essentially 

 as nutrient matter or sources of energy rather than as part of the 



