34 INTRODUCTION 



not be carried about in it, and hence chemical reactions could 

 not occur. It is this fact that makes the inorganic salts of such 

 vital importance to the cell life. To repeat Mann's words, it 

 is the electrolytes that put life into the proteids. Water itself 

 is almost absolutely nondissociated, and proteids so little that 

 for some time it was doubted if they really did ionize. Probably 

 all soluble substances do dissociate to a certain minimal degree, 

 but it is so slight for most of the constituents of the cell except 

 the inorganic salts (the organic acids and alkalies, and a few 

 dissociable organic products of proteid metabolism, occur in 

 such insignificant amounts as to be almost negligible) that 

 without them there would be little chemical activity possible, 

 and hence life would be absent or at a very low ebb indeed. 

 As before mentioned, the inorganic salts probably exist in the 

 cell not only as salts, but also, and perhaps chiefly, as ions 

 and ionic compounds with the cell proteids. For the most 

 part it seems to be the cations that play the chief role in forming 

 ion-proteid compounds, although undoubtedly the anions do 

 combine with the proteids also, and in some instances they exert 

 very characteristic and important effects ; e. g. } the differences 

 between the effects of chlorides, bromides, and iodides, or of 

 CNH as compared with HC1, both of which liberate the same 

 cation and differ only in their anions. 



Many applications of the facts and theories of ionization 

 have been made in physiology, as, for example, the observation 

 of Kahlenberg and True that taste is produced by ions rather 

 than by whole molecules; of Loeb, on the effects of ions upon 

 the taking up of water by the cells and tissues, their effects 

 upon muscular contractions, and upon cell multiplication and 

 fertilization; of Mathews, upon the transmission of nervous 

 impulses ; of Hardy, upon the effects of ions on coagulation and 

 precipitation of colloids. A few applications have also been 

 made in pathology, especially the relation of ions to edema, to 

 diuresis and glycosuria, and also to problems of immunity. 

 No attempt will be made here to go further into the observations 

 and theories concerning ionization or its role in physiology, but 

 for more extensive information as well as for the complete 

 bibliography the works mentioned below may be referred to. 1 



1 " Physical Chemistry for Physicians and Biologists, " Cohen. American 

 translation by M. H. Fischer, 1903; New York. " Physikalische Chemie 

 der Zelle und der Gewebe, " Hpber, Leipzig, 1902. " Osmotische Druck 

 und lonenlehre in den medicinischen Wissenschaften, " Hamburger, Wies- 

 baden, 1902. "Studies in General Physiology," Loeb, University of Chicago 

 Press, 1905. "Dynamics of Living Matter," Loeb, Columbia University 

 Press, New York, 1906. 



