INDIVIDUAL VARIABILITY. 



3T 



ASH ANALYSES. 



To determine -whether or not the amount or the composition of the 

 ash in the seed could be correhited with the resistance of the seedlings 

 to saline solutions, analyses of seeds of each variety used and of the 

 same origin as those used in the culture experiments were obtained 

 through the Bureau of Chemistry of the Department of Agriculture. 

 The results fail to show any correlation between the ash constituents 

 of the seeds and the resistance of the seedlings in water cultures. As 

 llie absence of such correlation is important, the table of analyses is 

 inserted. It is a surprising fact that some of the ash constituents 

 run very low for varieties such as Padui and Kharkof, in which one 

 would expect them to be high. 



Table of analyses of the ash constituents of wheat seedlings. 



INDIVIDUAL. VARIABILITY. 



Individual variation within the different varieties is a subject 

 deserving some attention in this connection. Some very striking 

 instances have been noted during the course of these experiments. 

 Since it has been demonstrated beyond dispute that the varieties 

 differ one from another in resistance to toxic salts, it is only natural 

 to suppose that the individuals of the same variety would show 

 diversity in this respect. It is the existence of this individual varia- 

 bility that has made it impossible to obtain reliable results without 

 testing a large number of seedlings. As soon as this factor was 

 eliminated it became comparatively easy to estal)lish the toxic limit. 

 In some instances it was more difficult than in others, and some varie- 

 ties were especially troublesome in this respect. The reasons for this 

 are difficult to determine. 



No experiments have been conducted for the exclusive purpose of 

 demonstrating the range of individual variation, and only results 

 are here recorded which have been l)rought out incidentally during 

 the tests for varietal variation. The writer does not doubt that 

 experiments with this end in view would l)ring out instances of indi- 

 vidual variability much more striking than any so far obtained. 

 Nearly all varieties, however, have shown exceeding diversity in the 



