52 Effect of Arsenic Compounds 



Arsenic per 100 parts fresh substance in fj.gr. (= thousandth part of a milligram) 1 . 



Wheat (Victoria complete grain) '7 



(from Tranche Comte) '85 



White bread -71 



Whole green cabbage '2 



Outside leaves of cabbage -0 (absent) 



Green haricots -0 



Turnip -36 



Potatoes 1-12 



Arsenic was also found in wine and beer and in considerable quanti- 

 ties in sea water and various kinds of salt. Since it cannot be found in 

 some things even in the least traces, the authors conclude that it is 

 incorrect to say that the element is always present or that it is essential 

 to all living cells. 



S. H. Collins (1902) found that barley is able to absorb relatively 

 large quantities of arsenic. The plants were grown in pots on soil which 

 originally contained a certain amount of the substance, and various 

 combinations of arsenic acid, arsenious acid and superphosphate were 

 added. Particulars and details are not given by the author, except that 

 arsenic was detected by Reinsch's test in the grains from all the experi- 

 mental pots, and in one case (not specified) in the upper and lower 

 halves of the straw and in the threshed ears. The analyses of the soil 

 at the close of the experiments showed the presence of 7 22 parts 

 arsenious acid per million. 



Wehmer (1911) quotes references to the occurrence of arsenic in 

 Vitis vinifera. The element was detected in the ash of the must and 

 its presence was attributed to treatment of the plants with arsenical 

 compounds. In this connection it is interesting to note the observation 

 of Swain and Harkins (1908), who, while acknowledging the absorption 

 of arsenic from the soil by many plants, yet indicate that in the case of 

 those plants which are exposed to smelter smoke the arsenic is deposited 

 on the vegetation, and is not absorbed by the latter from the soil. 



II. EFFECT OF ARSENIC ON THE GROWTH OF HIGHER PLANTS. 



1. Toxic effect. 



(a) Toxic action of arsenic compounds in water cultures in the presence 



of nutrients. 



The poisonous action of arsenic on plants has long been recognised. 

 Chatin (1845) gave accounts of tissues poisoned by strong arsenical 



r> , 1 = 0-0001 mg. 



