9O . LON A. HAWKINS 



Wo. Ostwald, 30 from his studies on Gammarus, concludes that the toxicity 

 of a solution is related to the power of the protoplasm to adsorb the dis- 

 solved substance, saying " dass eine Losung um so giftiger istje starker 

 sie adsorbiert wird." Morowitz 31 somewhat similarly considers that the 

 toxic salt is adsorbed by the surface layer of the organism and diffuses 

 thence into the interior, the amount thus entering in a given time being 

 related to the rate of adsorption. He supposes that, if an otherwise indif- 

 ferent but strongly adsorbed substance be simultaneously present in the 

 medium, the adsorption of the latter decreases the power of the surface 

 layer to adsorb the toxic salt, so that a smaller amount of this enters the cell. 



True and Gies [03] also relate these antagonistic effects to protoplasmic 

 properties, and seem to consider the antagonism between copper and calcium 

 to be due to an accelerating effect of calcium acting against a retarding 

 influence exerted by copper. Sziics [12], as has already been mentioned, 

 likewise supposes the influence of one salt upon the toxicity of another to 

 be due to simultaneous effects of the two salts upon the protoplasm. 



Loeb 32 has rather recently advanced the theory that the influence of one 

 salt on the toxic action of another is due to changes brought about in the 

 outer colloidal membrane of the protoplasm, whereby the latter becomes 

 impermeable to the toxic salt. Osterhout, 33 working with cut disks of 

 Laminaria and his method of electrical conductivity, also comes to the con- 

 clusion that ([12], page 115)" the antagonistic action of salts is largely or 

 entirely due to the fact that they hinder or prevent one another from 

 entering the protoplasm." 



It will be seen that any one of the various hypotheses just reviewed may, 

 with adequate quantitative assumptions, explain the phenomena of antagon- 

 ism as these are exhibited by any particular pair of concentrations of any 

 particular pair of salts dealt with in the present study. It seems, impos- 

 sible, however, to formulate a hypothesis, either by means of any of these 

 published suggestions or with any other logical possibilities, which may 

 simultaneously and satisfactorily account for all the cases with which we 

 have to deal. The marked differences, brought out in the present studies, 

 between the behavior of calcium when employed with copper and that of 

 the same element in combination with lead, zinc or aluminum, strongly 

 suggest the probability that valence alone does not determine the efficiency 

 of one cation in influencing the toxicity of another. It appears that other 

 properties must be taken into account if such differences are to be explained. 



30 Ostwald, Wo., Ueber die Beziehungen zwischen Adsorption und Gifti^keit von Salzl<">sum?en fur 

 Susswassertiere (Gammarus). Archiv. Ges. Physiol. 120: 10-30. 1007. 



31 Morowitz, Huso, Ueber Adsorption und Kolloidfalluns;. Kolloidchem. Beih. i: 301-331. IQIO. 



32 Loeb, J., The mechanistic conception of life. Chicago. 1912. Page 173. 



33 Osterhout, W.J.V., The permeability of protoplasm to ions and the theory of antagonism. Science 

 N.S. 35: 112-115. 1012. 



.Some quantitative researches on the permeability of plant colls. Plant World 16 : T 20-144. 1013- 



