7 



ite on plant growth depends upon the resisting power of the 

 plant and upon the chemical and physical nature of the soil. It 

 might be said that in small quantities the plant growth is stimu- 

 lated in most instances, but when added at the rate of .10 to .25 

 per cent, plant growth is practically impossible. No fertilizers 

 were added to these pots and it is highly probable that their addi- 

 tion might influence the action of he arsenic. 



The accompanying plate (Figs. 1, 2 and 3) illustrates more 

 clearly the effect of this chemical. All photographs were taken 



Fig. 3 — Buckwheat — Soil No. 3 

 From left to right, pots No. 8, 1, 2,3, 4, 5. 



when the plants were about 1 month old, and some of the most 

 -united plants died before reaching maturity. 



Arsenic determinations were made on all plants from pots 

 numbered 4, 5 and 6. The Marsh apparatus was used in the 

 analysis as described in II. S. Dept of Agr., Bur. of Chem., Bui. 

 113, p. 61. It was found to be present in all plants grown in these 

 pots, but not in weighable amounts, working on a 5 gram sample, 

 except pots No. 5, millet and buckwheat grown on soil No. 3. In 

 the former case it amounted to .0018 per cent and in the latter 

 .0053 per cent. This indicates that the arsenic passes from the 

 soil into the plant tissues and that when present in the plant . in 

 minute quantities growth is materially stunted. 



