45 



proteids. The salt or electrolyte iriolecules do not enter into this 

 combination as a whole, but through their ions. The great impor- 

 tance of these ion-proteid compounds lies in the fact that by the 

 substitution of one ion for another the physical properties of the pro- 

 teid compounds change. We thus possess in these ion-proteid com- 

 pounds essential constituents of living matter which can be modified 

 at desire, and hence enable us to vary and control the life phenomena 

 themselves. * * * If it be true that life phenomena depend upon 

 the presence of a number of various metal proteids (Na, Ca, K, and 

 Mg) in definite proportions, it follows that solutions ivhich contain 

 only one class of metal ions inust act as a poison. The reason for 

 this is that the one class of metal ions will gradually take the place 

 of the other metal ions in the ion-i^roteids of the tissues. Even a 

 pure NaCl solution must thus be i)oisonous, although this salt perme- 

 ates all our tissues and is the main constituent of the [soluble] inor- 

 ganic matter of the ocean. " ^ 



Pauli,- who i)ublished the same hypothesis almost simultaneously, 

 states his views with greater positiveness. "The general distribu- 

 tion of the ion-proteid compound in the living organism can not be 

 doubted; indeed, we have strong reasons for the assumption that all 

 the proteids of the protoplasm exist there only in combination with 

 ions." And again, " Not salts, but salt-ions, are indispensable to the 

 organism."^ 



Loeb's experiments show that to the same ions or mixtures of ions 

 different animals or different organs or stages of development of the 

 same animal may react in a different manner. This was noted in the 

 case of embryonic as compared with fully developed tissue and with 

 myogenic as compared with nuerogenic contractions. Thus in pure 

 solution magnesium chloride is more favorable to the development of 

 fertilized eggs of the sea urchin than is sodium chloride, although the 

 latter causes while the former prevents rhythmical muscular contrac- 

 tion. On the other hand, as the predominant salt in a triple mixture 

 of chlorides (potassium and calcium being present in much smaller 

 quantity), sodium chloride favors, while magnesium chloride pre- 

 vents, the development of fertilized sea-urchin eggs.^ Calcium ions 

 prevent rhythmical muscular contraction, but allow the muscle to 

 retain its irritability much longer than is possible in a solution from 



1 Amer. Jonrn. Physiology, 3, 327 (1900). 



-Ueber physikalisch-chemische Methode und Probleme in der Medizin, 19, 

 Wien (1900). 



^Loew, although attempting no such extensive generaUzation, has touched upon 

 the question of ion proteids and their relation to vital phenomena in his discus- 

 sion of the harmf ulness to plants exhibited by magnesium salts in the absence of 

 calcium. (See Bui. No. 18, Div. Yeg. Phys. and Path., U. S. Department of 

 Agriculture, p. 42, 1899. ) 



■lAmer. Journ. Physiology, 3, 439 (^1900). 



