CHAPTER III 



EFFECT OF COPPER COMPOUNDS 



I. Presence of Copper in Plants. 



Copper has been recognised as a normal constituent of certain 

 plants for at least a century, so much so that in 1816 Meissner brought 

 out a paper dealing solely with the copper content of various plant 

 ashes. The ash of Gardamomum minus, of the root of Curcuma longa, 

 and of " Paradieskorner^," amongst others, were tested and all yielded 

 copper in very small quantity. Meissner was led to conclude that 

 copper is widespread in the vegetable kingdom, but that it exists in 

 such minute traces that its determination in plants is exceedingly 

 difficult. In 1821 Phillips made an interesting observation as to the 

 effect of copper on vegetation. Some oxide of copper was accidentally 

 put near the roots of a young poplar, and soon after the plant began to 

 fail. The lower branches died off first, but the harm gradually spread 

 to the topmost leaves. As a proof that copper had been absorbed by 

 the plant the record tells that the blade of a knife with which a branch 

 was severed was covered with a film of copper where it had been 

 through the branch, and the death of the plant was attributed to the 

 absorbed copper. 



After this preliminary breaking of the ground little more seems to 

 have been done for some sixty years, but from about 1880 till the 

 present day the association of copper with the vegetable kingdom has 

 been actively investigated in its many aspects. Dieulafait (1880) 

 showed that the quantity of copper present in the vegetation is largely 

 determined by the nature of the soil, which thus affects the ease with 

 which the element can be detected and estimated. Copper was shown 

 to exist in all plants which grow on soils of " primary origin " (" roches 

 de la formation primordiale "), the proportion being sufficient to enable 



^ These are " grains of Paradise," Guinea grains, or meleguetta pepper. They are the 

 seeds of Amomum meUgueta and A. Granum-Paradisi, N.O. Zingiberaceae. 



