CHAPTER V 



EFFECT OF ARSENIC COMPOUNDS 



I. PRESENCE OF ARSENIC IN PLANTS. 



THE occurrence of arsenic as an occasional constituent of plants has 

 been recognised for many years. Chatin (1845) found that if a plant 

 were supplied with arsenical compounds at the roots arsenic was 

 absorbed, but that it was distributed unequally to the various tissues. 

 The greatest accumulation of the element was in the floral receptacle 

 and the leaves, while it was scarce in the fruits, seeds, stems, roots and 

 petals. E. Davy (1859) commented on the presence of arsenic in plants 

 cultivated for food. He grew peas in pots and watered them for a short 

 time with a saturated aqueous solution of arsenious acid, the application 

 being then discontinued. The plants, apparently uninjured by the 

 treatment, flowered and formed seeds. On analysis arsenic was readily 

 detected in all parts of the plant, including the seeds. Other analyses 

 revealed the presence of the element in cabbage plants (from pots) and 

 turnips (from field), both of which had been manured with superphos- 

 phate containing some amount of arsenic. This absorption of arsenic by 

 the roots of plants was further established by Phillips (1882). 



Various physiological workers have pointed out that this element is 

 frequently or usually present in animal tissues. Cerny (1901) reached 

 the general conclusion that minimal traces of arsenic can occur in animal 

 organisms, but that these play no part in 'the organism and indeed are 

 not constant in their occurrence. Bertrand (1902) established its 

 presence in minute quantities in the thyroid glands of the ox and pig, 

 hair and nails of the dog, and the feathers of the goose. Gautier and 

 Clausmann (1904) realised the constant presence of arsenic in human 

 tissues and recognised that it must inevitably be introduced into the 

 body with the food. This led them to estimate the arsenic present in 

 various animal and vegetable foods, some of their results being given in 

 the following table. 



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