ION-PROTEID COMPOUNDS 547 



or K solutions to the NaCl solution, it will no longer cause 

 rhythmical contractions in a fresh muscle. It therefore 

 looks as if the substitution of certain quantities of Na ions 

 for Ca ions caused contractions ; but if this substitution goes 

 too far, the muscle loses its irritability. On the other 

 hand, the presence of Ca ions in the NaCl solution prevents 

 the substitution of a sufficient number of Na ions for Ca 

 ions, and in the muscle thus prevents rhythmical contrac- 

 tions. It is due to the presence of Ca (and K) ions in our 

 blood that our muscles do not contract rhythmically. 



These facts received further support when I tried to 

 determine the active alkalinity of the blood. I had found 

 that a slight decrease in the active alkalinity of sea-water 

 retarded the development and growth of young sea-urchins, 

 while a slight increase in the number of hydroxyl ions 

 accelerated both processes. It seemed to me that the main 

 physiological interest in the alkalinity lay in the osmotic 

 pressure of the free HO ions in the blood or serum, as 

 only the free HO ions can have any physiological effects. 

 In the course of my experiments I found that the quantity 

 of free HO ions in the blood is neither increased by a 

 considerable addition of NaHO nor decreased by a con- 

 siderable addition of HC1. 1 Experiments proved that this 

 is not due to the salts of the blood or serum, but to the 

 proteids. It is evident that the latter have the power of 

 combining with H and HO ions. Spiro came to a similar 

 result by starting from a different point of view. 2 Here 

 again we have to deal with ion proteids. 



If we look at this phenomena from a biotechnical view- 



1 SPIRO AND PEMSEL, Zeitschrift far physiologische Chemie, Vol. XXVI (1898), 

 p. 233. 



2 The experiments consisted in this, that I added various quantities of acid or 

 alkali to ox blood and examined how long the muscle of a frog remained alive in 

 such a solution. While the addition of a small amount of acid or alkali to a 

 physiological salt solution renders the latter toxic for the muscle, a very much larger 

 quantity of acid or alkali is required to make the blood toxic for the muscle. 

 [1903] 



