Physiological Observations 



195 



TABLE XXVII 



Observations on the Saturation with Copper op Protein in Roots 

 Grown in Soil Treated with Cu(OH)2.CuC03 



While the figures on saturation in the hist column of the 

 table vary without reference to the amount of copper in the 

 soil and the degree of injury observed in the roots, yet they all 

 show a very low ratio of copper found to copper required for 

 saturation of protein present. 



In both wheat and peas, injury was first shown at 0.02 per 

 cent of copper in soil, increasing greatly with higher percentages. 

 This injury, showing as a characteristic crinkly condition, is 

 best seen in wheat and corn and has been observed in wheat 

 roots growai in a soil containing as little as 0.017 per cent of 

 copper. 



A further quantitative study of copper effects on root sys- 

 tems was carried out in water culture with corn, wheat, and 

 Canada peas. Paraffin (parowax) disks one-third of an inch 

 thick and nine inches in diameter were employed, perforated 

 with holes of suitable diameter by means of steel cork borers. 

 These disks were supported on paraffin posts tw^o and one-half 

 inches high in four-quart deep graniteware pans containing the 

 water culture solutions which were used. After soaking, the 

 germinating seeds were planted in paraffin disks of suitable 

 perforation and nutrient solution was then poured up to level 

 of contact with seeds. At first tap-water was used; then a 

 nutrient solution made up as follows : 



