13 



ever, in which careful analyses were made, arsenic was found 

 to have heen absorbed into the substance of grasses. 6 



The most extensive study of the effect of the absorption of 

 arsenic upon plants has been carried out by Headden. 1 Many 

 fruit trees, both apple and pear, were observed to be in a sickly 

 condition or dying in the orchards of Colorado which had re- 

 ceived arsenical sprays for from 20 to 40 years. An examina- 

 tion of the soil under such trees showed the presence of arsenic 

 in varying quantities, the highest being 138 parts per million. 

 In some cases where sickness or death of the trees was observed 

 the arsenic content of the soil was at least ten times that of nor- 

 mal soils in that locality. The orchardists were found to have 

 been applying for years what must be considered as excessive 

 amounts of arsenic. In some cases as much as 0.9 of a pound per 

 tree. In a period of six years this would amount to 432 pounds 

 per acre or about 108 parts per million in the first foot of soil. 

 The first symptom of poisoning in the orchard trees was a pre- 

 mature yellowing of the leaves. If the application of the arseni- 

 cals was repeated the next year the trees died the second year. 

 Serious injuries were also produced in these orchards- from the 

 corrosive effect of the arsenic which ran down the trunks of the 

 trees. The bad effects were most noticeable at the collar of the 

 trunk near the surface of the ground. 



In view of the somewhat divergent opinions which have thus 

 far been expressed relative to the effect of arsenic upon plants, 

 we may well inquire what may be considered the outlook from 

 the continued use of arsenite of soda as a weed destroyer in 

 Hawaii. The results announced by Headden and referred to 

 above have been called in question by other writers but without 

 substantial evidence to disprove his position. Our experience in 

 Hawaii is of only two years' duration. In a letter from Mr. W. 

 A. Anderson of Nahiku, Maui, the following statement is made 

 on the point under consideration : 



"As you know, we have been using the spray for nearly two years 



6 Jour. Am. Chem. Soc. 30 (1908), pp. 915-946. 

 i Colo. Sta. Buls. 131 and 157. 



