44 WHEAT RESISTANCE TO TOXIC SALTS, 



this fact, and is oi the opinion that substances acting as stinuihmts 

 are in the long run injurious. 



It is of course an established fact that certain of these salts are 

 beneficial and even necessary in particular cases. It has been claimed 

 that chlorids are indispensable to buckAvheat. The i^lant thrives 

 Avell until it has passed the blooming stage, at a period Avhen potas- 

 sium chlorid seems necessary to complete the fruiting stage. This 

 fact has apparently been demonstrated by experiment. Loew '^ 

 says that fungi grown in culture solutions containing only traces of 

 magnesia form no spores, but by increasing the amount of lethicin 

 and thus adding more magnesium to the culture solution spores will 

 be formed. ^lagnesium salts are as indispensable to fungi as to 

 high(>r plants, but an exceedingly small amount is sufficient when the 

 solution has an acid reaction. 



Plants are often benefited by sodium salts.'' AVhile three of these 

 salts — the chlorid, bicarbonate, and carbonate — are not indispensable 

 to the plant, they accelerate ripening in some of the cereals. 



Loew asserts that sodium, manganese, and silicon are often bene- 

 ficial but not indisj^ensable to phanerogams. Sodium salts are not 

 essential in the iDliysiological processes of plants, but are indispen- 

 sable to animals. 



PRACTICAL VALUE OF RESTJLTS. 



There is certainly a very practical lesson to be drawn from the 

 results described in this paper. It has of course long been known 

 that plants of difl'erent genera and species show very difterent 



a The Physioloarical Role of Mineral Nutrients in Plants. Bui. 45, Bureau of 

 riant Industry. V. S. Dept. of Airriculfnro (10(t:^). 



^ Chittenden and Waehsnian are of the opinion that the conversion of starch 

 into dextrin and sugar (diastase) is more vigorous in the presence of small 

 (quantities of sodium chlorid (0.24 per cent). Several investigators, prominent 

 among whom are Sprengel andT,iebig, have shown that various crops, and more 

 especially beans, are nmeh benefited by the application of small quantities of 

 common salt. 



Pethybredge ( P.ot. ("entralbl.. No. :',?>, 1001) is authority for the statement 

 that the color of wheat leaves is intensified when sodium chlorid is applied. 



S. .Suzuki (Bui. Coll. Agric. Tokyo, 5: No. 2. p. 10!)) showed that potassium 

 iodid, even in very high dilutions, exerted a stimulating action on the growth 

 of the ]>ea: and (ibid.. No. 4. p. 473) that dilute (piantities of potassium iodid 

 stimulated oats. In o]»[)osition to these stimulating effects the same investiga- 

 tor has found (ibid.. No. 4, p. 513) that vanadin sulphate, even in very dilute 

 quantities, produced little or no stinuilating action on barley, though he 

 states that a very weak stimulating action on the roots seemed to have taken 

 jlace in a 0.01 per mille of vanadin sulphate, lie. further shows (ibid.. No. 2) 

 that potassium ferrocyanid acts .-is a poison on jilants in water cultures even in 

 ^ery high dilutions. 



