A METHOD OF DETERMINING THE RELATIVE TOX- 

 ICITY OF SODIUM, POTASSIUM, LITHIUM, AND 

 OTHER IONS TOWARD ENDOTHIA PARASITICA: 

 DATA ON SODIUM CHLORIDE 



M. R. MEACHAM, J. H. HOPFIELD AND S. F. ACREE 

 Received for publication February 27, 1920 



In making a detailed chemical program in cooperation with Dr. 

 Caroline Rumbold and in connection with her investigations 1 on 

 the injection of trees with chemicals to bring about immunity 

 against attack by fungi and bacteria, it was considered im- 

 portant to conduct a laboratory study with culture media on the 

 relative toxicity or effect of the molecules, anions and cations of 

 various sodium, potassium, lithium, calcium and other salts. 

 As the lithium salts which Dr. Rumbold found most effective were 

 not readily available during the War, the present paper deals 

 with the toxicity of sodium chloride. 2 If a constant hydrogen 

 ion concentration near the optimum for Endothia parasitica 

 (Murr.) Anders, were used in the media and if the salts were com- 

 pared on the basis of chemically equivalent quantities with a 

 common anion, it was thought that the tests would show the 

 relative toxicity of both the cations and nonionized molecules of 

 each salt. Knowing tfre relative concentrations of the cations 

 and nonionized form of a given salt present in decreasing quantity 

 in a series of samples of the medium, it is easy to calculate the 

 activity of the different ionic or molecular species from a series 

 of simultaneous equations having the form (1) which was 



1 The injection of chemicals into chestnut trees. American Journal of Botany 

 6: December, 1919. 



2 Ferdinand Wolesky stated in Papier Zeitung, 21: 563 (1896) that 0.05 per cent 

 solutions of sodium chloride prevent the growth of organisms on wood pulp. 

 Such a high toxicity for sodium chloride, corresponding to the best creosotes, is 

 not substantiated by the present work in which 75 times as much sodium chloride 

 decreased the growth only to 25 per cent of its normal value. 



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