J. J. GrRIFFITH 387 



Absorption of Lead by the Plant. 



The question which often arises in connection with the poisoning of 

 stock is whether lead is absorbed by the plant. Analysis of the herbage 

 of affected land, and also of the crops grown in pot experiments, almost 

 invariably revealed the presence of lead. In one particular case the 

 following results were obtained with the ash of the herbage of a badly 

 affected area. The sample was divided into three lots, which were dealt 

 with separately as indicated below. 



{a) Lead in ash of untreated sample 3'63 per cent. Pb. 



(6) Lead in ash of beaten or thrashed sample -46 ,, ,, „ 



(c) Lead in ash of washed sample -12 ,, ,, ,, 



The presence of lead on the exterior of the plant as a result of 

 splashing and wind action renders the method indicated above unsatis- 

 factory for the purpose of ascertaining whether lead enters into the 

 composition of the plant. This difficulty was eliminated in the following 

 experiments : 



(a) Swedes grown in an affected field were carefully washed and 

 peeled. The central portions of the roots were dried and ignited. The 

 ash was found to contain -03 per cent, of lead. The amount of lead 

 contained in the soil upon which the swedes grew varied from -1 jjer 

 cent, to -4 per cent. Pb. 



(6) Oats were grown in i)ots containing contaminated soil (with 

 •41 per cent. Pb.) covered with a layer of sand. The ash of the crop 

 contained -07 per cent, of lead. 



Lead, therefore, enters into the composition of plants growing on 

 affected soils only in very minute quantities. Consequently injurious 

 effects upon animals are likely to be due largely, if not mainly, to the 

 lead in the deposit on the exterior of the plant, or to what may be 

 picked up from the soil itself by close grazing. 



Pot Experiments. 



Infertility in mine affected soils may be due to the simultaneous 

 influences of a number of circumstances. Consequently pot experiments 

 were performed with a view to isolating the factors. Additional experi- 

 ments were carried out in order to ascertain the effects upon different 

 crops and also to discover possible remedial measures to restore fertility. 



On account of the liabilit}' of distilled water, and of rain water 

 collected under circumstances which involve contact with paint or metal 

 work, to contain metallic impurities, a special collecting surface was 



