Permeability 137 
and strontium. Antagonism was also found between barium and 
potassium, barium and magnesium, and between strontium and the 
following: potassium, sodium and magnesium. McCool also observed 
antagonism between sodium and potassium and between sodium and 
ammonium. The poisonous action of manganese is reduced by the 
presence of calcium, potassium, sodium or magnesium. 
Antagonism can also be demonstrated by means of determinations 
of the electrical conductivity of living tissue. It has been mentioned 
earlier that dead tissue possesses a much greater electrical conductivity 
than living tissue. Osterhout (1912 a , 1914/, 1915 b) showed that 
tissue of Laminaria lost in electrical resistance much more rapidly 
in a solution of sodium chloride having the same conductivity as 
sea water than in a solution of pure calcium chloride of the same 
conductivity, while in a solution of this same conductivity containing 
sodium chloride and calcium chloride in the proportion of 1000 mole¬ 
cules of the former to 15 of the latter, Laminaria maintained its 
original resistance for 24 hours, indicating that in the mixed solution 
the cells of the alga remain alive considerably longer than in pure 
solutions of the same conductivity. By this method antagonism has 
also been demonstrated between sodium chloride and magnesium 
chloride, sodium chloride and hydrogen chloride (Osterhout, 1914 i, 
1915 a), sodium chloride and sodium taurocholate (Osterhout, 1919 b) 
and between sodium chloride and a purine, caffeine, and an alkaloid, 
cevadine sulphate (Osterhout, 1919 d). Antagonism between sodium 
acetate and sodium sulphate, and also between sodium citrate and 
a number of other sodium salts (chloride, sulphate, nitrate, iodide 
and thiocyanate) has been shown by Raber (1917,1920 b) by the same 
method. 
Brenner (1920) considers that he has demonstrated the existence 
of antagonism between hydrochloric acid and a number of salts by 
the following experiments. He had earlier (1918) examined the 
resistance of hypodermal cells of red cabbage to acids and alkalies 
in low concentrations, using plasmolysis and deplasmolysis as tests 
of the vitality of the cells examined. Pieces of tissue were placed in 
a solution of 20 per cent, sucrose containing the acid in definite con¬ 
centration and left in it for the experimental time (ten minutes to 
four hours). The pieces of tissue were then transferred to 10 per cent, 
sucrose, then into 5 per cent, sucrose for 30 minutes and, finally, 
into distilled water for the same length of time. If the cells de- 
plasmolysed normally they were considered to be living. If dead, 
the protoplast was either disorganised or was in a fixed plasmolysed 
