COMPARISON OF RESULTS. 



35 



ety and Preston a variety from Canada. The soil and climatic condi- 

 tions are very similar. Both regions are comparatively humid, Avith 

 little or no saline soil. Both of these varieties are low in resistance to 

 salt solutions, just as would be expected. 



A comparison of the resistance Of the different varieties wi(h the 

 reo-ion from which thev came in resi:)ect to soil and climatic coudi- 

 tions shows that their resistance to saline solutions can probably be 

 correlated Avith the natural habitat of the varieties; that is, the 

 results herein obtained indicate that a variety grown in a locality 

 having little or no excess of salts in the soil has a comparatively low 

 resistance in saline water cultures. It further shows that varieties 

 «-rown in resfions havin"' more saline soils have a much greater resist- 

 ance in saline water cultures. 



COMPARISON OF RESULTS WITH DIFFERENT SPECIES. 



The results obtained for the lupines by Kearney and Cameron 

 and those for maize by Kearney have frefiuently been referred to in 

 the foregoing images. It has been possible to compare them to the 

 Avriter's results 'with Avheat only in a fragmentary way. Since there 

 are some very surprising differences in the toxicity of the same salts 

 to the three plants, the results have been brought together in one 

 table for comparison. Kearney and Cameron used but one variety 

 of the lupine and of maize, their results being shown in the follow- 

 ing table. The Avriter in his experiments on wheat has used nine 

 different varieties, but in the following table only the mean resistance 

 of all the varieties has l)een taken. 



The limit of concentration of the salts which can be endured by 

 wheat, lupine, and maize is as follows, the results being stated both in 

 fractions of a normal solution and in parts of salt per 100,000 of 

 solution : 



Salt. 



Parts of 

 a normal 

 .soluti(_)n. 



Magnesium sulphate 

 Magnesium chlorid . . 

 Sodium carbonate _.. 

 S xlium biearb< mate . 



Sodium sulphate 



Sodium chlorid 



Degree of concentration. 



Wheat. 



0.007 

 .009 

 .01 

 .026 

 .043 

 .054 



Parts per 

 100,(X)0 of 

 solution. 



Parts of 

 a normal 

 solution. 



39 

 108 



52 

 217 

 302 

 313 



Lupine. 



0.00125 

 .0025 

 .005 

 .02 

 . 0075 

 .02 



Pai'ts per 



KHMIOOof 

 sohition. 



Parts of iPartsper 

 a normal! I ()(),{ KK) of 

 solution, solution. 



12 

 2(5 



167 

 53 



116 



Maize. 



0.25 

 .08 

 .015 

 .05 

 .05 

 .04 



1,400 

 384 

 78 

 417 

 353 

 232 



It is remarkable that while magnesium sulphate is the most toxic 

 to the wheat and the lupine of all the salts used it is the least injuri- 

 ous to maize, being thirty-five times and two hundred times, respec- 

 tively, more toxic to wheat or lupine than to maize. 



