180 THE BOTANTCAL MAGAZINE IVoi. xxvu. N0.32. 



It is assumed that the plant is ill affected by the salts, if 

 the length of root be half that of control plants, even though 

 the length of leaf be greater than that of the control leaf. 



In this case, as in the previous experiment, the growth of 

 the seedlings was also injured or stimulated by each salt ac- 

 cording to the concentration. In the concentration at which 

 the toxic action ceases, the stimulating action began and at- 

 tained its highest point in certain dilution. The growth was 

 injured by magnesium sulphate in concentration greater than 



normal and highly stimulated by normal. Magnesi- 



100 & J J 500 



um chloride was also toxic in consentration greater than 



500 

 normal and attained highest stimulating point in concentration 



°f r-nnr^ normal. The toxic concentraction of calcium chloride, 

 5000 



sodium sulphate, sodium chloride, sodium carbonate and bi- 

 carbonate was each in concentration greater than -ftt> 

 -l .j _. 100 50 



Too"' 100 '' ~5(T norma l respectively and highest stimulation 

 was reached in dilution of -77^70 ., n ~ . „ ~~ , _^~ and 



1000 ' 100 ' 100 ' 500 500 



normal respectively. 



Now, for convenience of comparison, the concentration of 

 toxicity and stimulation of the seven salts in the two experi- 

 ments are brought together in the following table: (See p. 181.) 



As seen in the table, both results almost coincide on the 

 toxic and stimulating point. A slight fluctuation of these 

 points is probably due to the facts that the plant growth 

 varies to the certain extent with the temperature and other 

 factors, since these experiments were not carried on at constant 

 temperature and under identical conditions. 



