42 BOTANICAL GAZETTE [JANUARY 
elsewhere statea, such experiments have been made with garden 
loam and are unreliable because of the multiplicity of inorganic and 
organic substances with which the introduced poison may react. My 
results show that the introduction of pure quartz flour into a toxic 
solution, in such proportion as to form an ordinary moist soil, reduces 
the toxicity of the solution in a marked degree. But whether this 
reduction is due to adsorption, as TRUE and OGLEVEE would have it, 
or to a reduced freedom of movement of the solute particles, that is, 
a reduction of diffusion tension, as DANDENO suggests, or to some 
chemical changes enhanced by the quartz is yet an open question. 
2. Of the limited number of poisons tried, all gave stimulation 
results in quartz, and all but two—ZnSO, and CuSO,—in solution 
cultures. It is not beyond probability that these two, in proper 
concentration, might also be found to be stimulating. 
3. The more dilute the fatal dose in solution, the more the toxic 
effect is reduced by the introduction of quartz. Hence the range of 
concentrations, both fatal and accelerating, is much greater in solu- 
tion than in soil cultures. 
Finally, I wish to acknowledge the friendly cooperation of all 
members of the botanical staff of the university, and especially the 
stimulating suggestions of Professor CHARLES R. BARNES and 
Dr. B. E. Livrncston. 
LITERATURE CITED 
1. Aso, K., On the action of sodium fluoride upon plant life. Bull. Coll. 
Agr. Imp. Univ. Tokyo 5:n 
. BAUMANN, ANTON, Das Vaan von Zinksalzen, etc. Landw. Vers. Stat. 
3121-53. 1885. 
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3. BENECKE, W. , Einige neuere Untersuchungen iiber den ame. von Miner- 
alsalzen aul Organismen. Bot. Zeit. 627:113, 126. 1 
4. BopLANDER, G., Ueber die Léslichkeit der ‘<cae in kohlen- 
saiirehaltigen Wasser Zeit. Physik. Chem. 35:25. 1900 
BREAZEALE, J. F., Effect of certain solids paar S growth a seedlings in 
‘water cultures. Bot. GAZETTE 41:54-63. 
. Briccs, L. J., The mechanics of soil moisture. - ‘Ss. Dept. Agr., Div. of 
Soils, Bull. 10. 1897. 
. CAMERON, F. K., and BreazEAaLe, J. F., The toxic action of acids and salts 
on seedlings. Jour. Physical Chem. 8:1-13. 1904. 
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