TOXICOLOGY AND PHARMACOLOGY 379 



since the cilia dissolve. This injurious action is stopped by poly- 

 valent cations. 



Interesting in this connection are the experiments of Wo. OST- 

 WALD * l on the vitality of the sand flea (gammarus pulex) which lives in 

 fresh water. It survives in sea water three or four days but in a 

 mixture of four-fifths sea water and one-fifth distilled water, it lives 

 almost as long as in fresh water. If each constituent of the sea water 

 is successively removed, the toxicity of the remainder rises, that is 

 the duration of life diminishes in the following order: 



NaCl + KC1 + CaCl 2 + MgSO 4 + MgCl 2 

 NaCl + KC1 + CaCl 2 + MgS0 4 

 NaCl + KC1 + CaCl 2 

 NaCl + KC1 

 NaCl. 



According to W. J. V. OSTERHOUT what has been demonstrated 

 for animals is equally true for plants (algae, grains, liverwort and 



moulds). The fresh water alga, vaucheria sessilis, is killed in 



US4B 



NaCl solution but continues to grow if a trace of calcium chlorid is 

 added. According to CHAS. B. LIPMAN the dry weight of ripe 

 barley was increased if CaS0 4 was added to a culture containing 

 sufficient sodium sulphate to be harmful. In this case as with cul- 

 tures of bacteria, the antagonistic action of the cations play an 

 important part. 



Though we employ physiological sodium chlorid solution in many 

 experiments for the maintenance of isotonicity, it is merely a make- 

 shift, and on this account there have recently been introduced solu- 

 tions which, as well as being isotonic, have a composition similar to 

 the blood (RINGER'S and ADLER'S solution) and thus maintain its 

 normal state of swelling. [More recently MCCLENDON'S. Tr.] 



All these solutions contain the divalent Ca ion. We have indi- 

 cated on page 70 how we believe its detoxicating effect is brought 

 about; it opposes the swelling due to monovalent ions (Na, K). 

 And it is usually assumed that the " tanning" is limited to the plasma 

 pellicle. 



Though the cations are of major importance in "balanced" 

 combinations of salts, the anions are not without significance 

 (J. LOEB). 



As was mentioned previously, the toxic action of the neutral salts, 

 is, in general, reversible. On this account the question arises, 

 whether their action is due to a solution or an adsorption phenomenon 

 by the organ colloids. Wo. OSTWALD decided the question in favor 

 of the latter view. In the adsorption equation (see p. 21) in- 



