42 WHEAT RESISTANCE TO TOXIC SALTS. 



tions were in the exact proportion that wouhl have permitted tlie 

 greatest ek)neation. The ol>iect Avas merely to show that at the con- 

 centrations used in these experiments the salts of magnesium and 

 of sodium effectively neutralize the injurious element present in the 

 once-distilled water. The only noticeable difference Avas in the case 

 of sodium carbonate and sodium chlorid. in which the elongation was 

 somewhat below the average in the pure-water check and in the solu- 

 tions of other salts. The use of a more dilute or a more concentrated 

 solution would doubtless have removed this difference. On the other 

 hand, a 0.001 normal magnesium chlorid was conducive to better 

 development than any of the others. Avitli the single exception of 

 hydrant water. It Avill be noticed that at the end of the third day 

 there was even a slight advantage in favor of magnesium chlorid 

 over river water. 



The elongation the fourth day Avas but a slight increase over that 

 •a{ the end of the third. Avith the one exception of the seeds in the 

 hydrant Avater. This is just Avhat Avas to be expected. During these 

 four days the seeds Avere compelled to Hac on the nutriment stored up 

 in the endosperm. This had been jDractically all used up at the end 

 of the third day ; hence the cessation of grov.th. With hydrant Avater 

 the conditions Avere different. Certain nutritive substances are con- 

 tained in this Avater upon Avhich the roots can draAv Avhen those con- 

 tained in the endosperm have been exhausted. 



InvicAv of the experiments, small quantities of these sodium and 

 magnesium salts, instead of being injurious Avhen present in the 

 soil, might be actually beneficial in case the soil contains very toxic 

 substances, e. g., zinc or copper. In fact, these salts are injurious 

 only Avhen present in excessiA^e quantities, as in the so-called " alkali 

 soils "" of the West. 



DILUTE SOLUTIONS AS STIMULANTS. 



Incidentally, throughout these experiments, eA'idences of stimula- 

 tion in dilute solutions Avere obtained. This has been shown to 

 occur by many iuA'estigators Avith other salts and Avith some acids." 



Kearney and Cameron. Avho made similar observations Avhen ex- 

 perimenting Avith Lupinus alb us, say : 



In the f-ase of certain salts, when plants are exposed to pure sol-itions wliich 

 are nuu-h too dilute to produce any toxic effect, there occurred .i decidedly 



n Some fungi have heen known to he stimulated ))y the presence of small 

 quantities of poisons. Th^ germination of sjiores has likewise heen hastened 

 when in tlie presence of acids or salts. Townsend (Bot. Gaz.. 27 : J.lS—tOG, 1800) 

 found that the germination of various seeds and spores has heen stimvdated hy 

 the ])resence of traces of ether, and (Bot. Gaz.. .31: 241-2(!4, 1001) that the 

 presence <if hydrocyanic acid for a hrief period of time accelerates germination 

 and suhsequeut growth. 



