LIMITS OF ENDURANCE OF DIFFERENT FARM ODOPS. 



395 



It appears from the above that in the case of barley, 

 germination is affected by the presence of '005 per cent, 

 sodium chlorate in the soil, and entirely prevented when 

 '006 or *007 is present. The effect of this substance is 

 apparent when *003 per cent, is present, and when it reaches 

 '006 the growth of barley is prevented. 



Experiments ivith arsenious acid. 



Six pots received varying proportions of arsenious acid 

 on December 3rd, 1902, as follows : — 



No. 127, '10 per cent. As,O s ' 

 „ 128, '20 

 „ 129, -30 

 „ 130, *40 

 „ 131, *50 

 „ 132, -60 



All plants germinated fairly well, but the growth was 

 found (December 13th, 1902) to have been affected by the 

 smaller quantity of arsenic taken, No. 127 being very slightly 

 affected. No. 128 slightly affected, and in No. 129 the growth 

 of the plants was much affected, the effect being more 

 marked with the increase of arsenic in the remaining pots. 



Additional pots were resown on July 30th, as follows : — ■ 

 No. 133, *05 per cent. As 2 3 

 „ 134, '06 



,, loo, 1U ,, ,, 



When examined on August 21st, 1903, the germination 

 was practically unaffected in all cases, but the effect on the 

 growth was already strongly marked in the case of No. 133. 

 In No. 135 the growth was very strongly affected. By 

 September 29th, 1903, when the pots were again examined, 

 pots 133 and 134 had recovered and were growing vigorously 

 though not quite as strongly as the control pot. In No. 135 

 however, the plants were almost dead. 



