1917] Lipman-Gericke : Smelter Wastes and Barley Growth, 537 



habitat. Since plants are, after all, to be found growing natu- 

 rally only in soils, it cannot be a matter of indifference to us, 

 in attempting the study of the effect of a certain substance or 

 substances on them, whether they are supplied with normal 

 conditions for their development or not. 



Proceeding now to an examination of the results obtained 

 by other investigators on the effects of copper on plants grown 

 in soil or sand insjtead of solutions we find many interesting 

 observations. Injurious effects of CUSO4 at the rate of about 

 400, 800, and 1600 pounds per acre to potatoes and beans were 

 noted by Steglich,-*' but he failed to observe such toxic effects 

 on the same soil to strawberries or fruit trees. Haselhoff-' claims 

 also to have noted injury to grass, beans, and other plants from 

 smelter smoke containing copper. Owing to other conflicting 

 factors concerned in smelter-smoke injury, Haselhoff 's results 

 are open to serious criticism. Simon-^ experimented with oats 

 and mustard on garden soil, clay, and sand, and used amounts 

 of CuSO^ varying from 0.01 per cent to 10 per cent. His state- 

 ments imply that copper was toxic throughout, with the oat 

 plants showing more resistance than the mustard, and that 

 CUSO4 was least toxic in garden soil and most toxic in the sand. 

 Opposed to the three cases just cited are numerous results show- 

 ing the stimulating effects of copper to plant growth in soils. 

 We find among these the results obtained by Girard,-^ Kanda,"° 

 Jensen,"^ Voelcker,"- Forbes,^^ and Sachser.^^ A large number 

 of observations have also been made on the stimulating effects, 

 or lack of any effect, of copper sprays, and in other ways of the 

 effect following direct contact of the copper solution with plant 

 cells, among which maA' be mentioned those of Frank and 



26 Ber. Tat. Landw. Abt. K. Vers. Stat. Pflauzenkult, Dresden, p. 4, 

 1903; E. S. E., 16, p. 133. 



27 Fiililing's Landw. Ztg., vol. 57, no. 18, p. 609; E. S. E., 20, p. 831. 



28 Landw. Vers. Stat., 71, p. 417; E. S. E., 22, p. 439. 



29 C. E. Acad. Sci., Paris, 120, p. 1147; E. S. E., 7, p. 99. 



30 Jour. Col. Sei. Tokyo Imp. Univ., 19, p. 47 ; E. S. E., 16, p. 228. 



31 Bot. Gaz., 43, p. 11; E. S. E., 18, p. 625. 



32 Jour. Eoy. Agr. Society, England, vols. 73, 74, and 75, Eeport for 

 1912, 1913, and 1914. 



33 Univ. Calif. Publ. Agr. Sci., 1, no. 12, 1917. 



34 Cent. Agr. Cliem., 33, p. 533 ; E. S. E., 16, p. 865. 



