Permeability 135 
With regard to quantitative relations between the two ions, the 
quantity of the depoisoning ion required to inhibit the action of the 
poisonous ion varies with the concentration of the latter. Thus a 
concentration of 0-25 N NaCl is harmless to Fundulus eggs; with a 
concentration of 0-625 N NaCl one bivalent ion is required to render 
1000 sodium ions harmless. Between these two concentrations the 
number of bivalent ions relative to the number of sodium ions is less 
the lower the concentration of the sodium chloride, while above a 
certain concentration of sodium chloride it is impossible to inhibit 
the toxic action of the sodium chloride. 
These antagonistic effects only appear so long as the fish is 
surrounded by the egg membrane. Loeb concludes that the mem¬ 
brane is the seat of the antagonistic action, and that it is here that 
the ions mutually hinder one another in penetrating into the egg. 
Loeb’s work on antagonism in animals was followed up in plants 
by Osterhout, who devised a number of methods of attacking this 
question. In his earliest experiments antagonism in plants was 
examined by the reduction of toxic action in mixed solutions as 
compared with the toxicity of pure solutions containing the same 
substances in the same concentration. The first experiments were 
with marine plants (Osterhout, 1906 a, b, c). It was found that while 
some marine plants are quickly killed when placed in distilled water, 
others can live a long time in this medium 1 . The latter plants are, 
however, killed much more quickly when placed in a pure solution 
of sodium chloride isotonic with sea water. The toxic action of the 
sodium chloride is removed to a very great extent by the addition 
of a little calcium chloride, for in a mixture containing 1 c.c. of 3/8 M 
calcium chloride + 100 c.c. 3/8 iff sodium chloride, the plants live 
nearly as long as in distilled water. If some potassium chloride is 
added to the mixture the plants live longer than they do in distilled 
water, while with further addition of magnesium chloride and 
magnesium sulphate, the plants live practically as long as in sea 
water. 
The toxicity of sodium chloride is also reduced by the addition 
of potassium chloride or magnesium chloride, but not so much as 
by the addition of calcium chloride. The addition of potassium 
chloride + calcium chloride reduces toxicity more than magnesium 
chloride + calcium chloride, and this mixture more than magnesium 
chloride + potassium chloride. 
1 Possibly owing to exosmosis being less in the case of the latter (cf. Oster¬ 
hout, 19176). 
