504 University of California Publications in Agricultural Sciences [Vol. 1 



appartMit in the first five lowest concentrations of tlie CuSO^ 

 series. It did not show in the first two concentrations of ZnSO^. 

 but in all others, and was clearly manifest almost throughout the 

 potash alum series. In the FeSO^ series the heights followed 

 the general observations just recorded for the ZnSO^ series so 

 far as comparison with controls is concerned. As regards abso- 

 lute heights of plants the ZnSO^ series showed the highest, and 

 the potash alum series was a close second, with the others con- 

 siderably behind. 



It appears, therefore, that with regard to stimulation both 

 of tillering and of tallness, ZnSO^ is superior to the other salts. 

 The agreement between duplicate pots in respect to the height 

 of plants was far more satisfactory than that for tillering. None 

 of the actual data are given here because of the necessity for 

 brevity in such papers and because of the decidedlj' minor sig- 

 nificance of the results in connection with the main issue under 

 examination. 



Germination of Seeds 

 In all of the series under discussion, the germination of seeds 

 was more rapid in the salt-treated soils than in those untreated, 

 at least up to certain very considerable concentrations of the 

 salts. Exceptions to this rule were of course found in certain 

 concentrations of the salts which entirely inhibited growth and 

 in those which almost did so ; but in all pots in which the salt 

 concentrations were not of that order, germination was much 

 more rapid than in those which remained untreated. The stimu- 

 lation in respect to germination w^as about of the same degree 

 in all concentrations of every salt which would at all stimulate 

 germination, larger amounts of salts not differing from the 

 smaller ones. Certain definite differences, however, existed in 

 that regard among the different salts. Thus CUSO4 stimulated 

 germination most, ZnSO^ was second in order, PeSO^ third, and 

 the other salts exerted only a slight influence. Our findings in 

 this respect, therefore, are again in accord with those of Pam- 

 mel * and Van Slyke,^ which are above cited, and also with 



4 Iowa Agr. Exp. Sta. Bull. no. 16, 1892. 



5N. Y. (Geneva) Agr. Exp. Sta. Bull. no. 41, 1892. 



