1917] Lipman-Gericke : Smelter Wastes and Barley Growth 527 



Second Crop 



When the total dry matter of the second crop in the MnS04 

 series is considered (table IX&), we find that not only has the 

 stimulation noted in the first crop disappeared, but that an act- 

 ually definite toxicity has supplanted it. Moreover, such toxicity 

 is as marked with the lowest as it is with the highest concentra- 

 tions of MnSO^, and it is even possible that the former definitely 

 surpass the latter in that respect. Again, as in some preceding 

 cases with other salts, the total dry-matter yields do not give a 

 complete picture of the effects of MnSO^ on barley growth. Thus 

 if we consider the straw, grain, and root yields separately, we 

 find data leading to conclusions slightly different from those 

 above. For example, whereas both the grain and root produc- 

 tion are definitely depressed at all concentrations of MnSO^ in 

 the second crop, this is not so for the straw yields. The latter 

 are in many instances, including the cultures of the highest 

 concentrations of MnS04, increased by the effects of the salt. 

 Were it not for the lack of agreement in some of the duplicates, 

 we might add more emphatically that straw yields are markedly 

 stimulated by MnSO^ in the second as in the first crop on the 

 greenhouse soil. This seems particularly true at the higher 

 concentrations of the latter salt, but is also apparent at some 

 lower concentrations. Since, therefore, no grain was produced 

 in the first crop, and since only three of the lowest concentra- 

 tions of MnSO^ in it gave stimulation to root development, it 

 seems not unreasonable to consider that the results of the second 

 crop in the MnSO^ series are, in the large, not essentially differ- 

 ent from those of the first crop. The outstanding result is the 

 stimulation to straw production which is noted, and that is differ- 

 ent in degree only, not in kind, in the two crops here considered. 

 Despite all this, however, we do not attempt to disregard the 

 differences which characterize the effects of MnSO^ in the first 

 and second crops as above pointed out, but we regard them as 

 of minor significance. 



When we compare MnSO^ in the second crop with other salts 

 under similar circumstances in the greenhouse soil, we find that 

 it has but little in common with them. It approaches perhaps 

 most closely the behavior of PbSO^ in the second crop, but is 



