ELECTROLYTES IN LIVING MATTER 77 



and development upon the salts dissolved in the sea water. If the 

 young fish, however, are put into a pure solution of NaCl of the concen- 



(tyyi \ 

 -). the animal 

 2/ 



dies in less than twelve hours. If CaCl 2 is added, the animal does not 

 live more than twenty-four hours. If it is desired to keep animals 

 alive permanently, - - my experiments lasted for ten days, - - not only 

 2 CaCl 2 but also 2 KC1 must be added to 100 NaCl. This is exactly the 

 solution which is generally considered as a nutritive solution for animals.* 

 I believe that these facts show that we must discriminate between 

 nutritive and protective solutions. Ringer's solution, as well as the 

 sea water, are primarily protective and not nutritive solutions. What 

 is meant by this becomes clear if we remember what was said concern- 



*>yi 



ing the antagonistic effects of salt. A - - solution of NaCl, as well as a 



Wl 



'- solution of ZnSO 4 , alone are each poisonous for the eggs of Fundulus. 

 4 



If mixed, the solution becomes considerably less poisonous. It is prob- 

 able that these two salts if together in solution materially diminish 

 their rate of diffusion into the tissues. It follows from these experi- 

 ments that the role of the Ca and Mg in the sea water, as well as in a 

 Ringer's solution, consists partly in antagonizing the effects which would 

 be produced by the NaCl were it alone in solution. The experiments 

 with Fundulus suggest that in this case the presence of the Ca and Mg 

 in the sea water diminishes the rapidity of diffusion of the NaCl into 

 the tissues. It is possible that the Zn acts in some protective way in 

 the case of Raulin's solution, although in regard to this it is not 

 possible to make a definite statement. 



But there remains the other fact that K is also needed. The life 

 of Gammarus and many other marine animals is not essentially pro- 

 longed by the addition of CaCl 2 or MgCL, or both to the NaCl solution, 

 but is materially prolonged by the addition of CaCl 2 and KC1 to the 

 NaCl solutions. Besides we cannot, in general, substitute any other 

 bivalent metal (with the exception of Sr) for Ca; nor can we sub- 

 stitute any other univalent cations for Na and K. This indicates 

 that the metals Na, Ca, K, and Mg play a role in life phenomena other 

 than that of serving for the synthesis of living matter, and also other 

 than that of merely regulating the velocity of diffusion. We have 

 already alluded to the possibility of their necessity for phenomena of 

 secretion. We are inclined to believe that what is generally called 

 irritability and contractility is due to the influence of these ions. 



* Loeb, Pfluger's Archiv, Vol. 55, p. 530, 1893. 



