i8 
Colorado Experiment Station 
killed. Not being fully satisfied about the facts connected with this 
tree, I determined to examine its roots. I found two roots affected, 
one’was still partly alive, the other was entirely dead. Neither of 
these roots was very large, a scant inch in diameter, but we traced the 
wholly dead one for twelve feet then we trenched across its course, at 
several points and thus traced its dead rootlets to the stump on w hich 
the arsenic had been poured, 22 feet from the trunk of the tree. These 
roots presented externally the same appearances as the root previously 
described and is well represented by Plate III, reproduced from Bul¬ 
letin 131. The other roots of this tree which we encountered were 
apparently normal. I examined several samples of wood from the 
first tree'and found arsenic abundantly present and determined the 
quantity of arsenic present in the woody tissue of the root. The amount 
of arsenic present in the woody portion of the root of the 
first tree after the bark had been pared off corresponded to 3.4.5 parts 
of arsenic acid per million parts of tissue. The arsenic in the 
root of the second tree described corresponded to 24.02 parts of arsenic 
acid per million oarts of tissue. The disintegration of the root was 
certainly remarkable. 
PLATE ill. 
I have information of several other instances in which similar re¬ 
sults have been produced. According to the statements of the owners 
it seems probable that the arsenite of lime might have done the damage 
to their trees. 
Mr. A. B. Hoyt, Horticultural Inspector of Mesa County, informs 
me that he has seen a cottonwood and a willow tree killed by the burst¬ 
ing of a jug of sodic arsenite which had been left beneath them. 
I have the record of some other trees killed in a similar manner. 
These cases are cited that we may present the effects of arsenic 
upon the tree and its tissues when it is present in the soil in a soluble 
form and in sufficient quantities to kill quickly. 
We find in these cases the following features: the disintegration 
of the bark and woody tissues of the roots, the killing of the bark and 
tissues of the trunk, the production of a black heart, the exudation of 
ill smelling juices and a stunting in cases where a portion of the limb 
has survived. 
The arsenite of soda mentioned above is the solution of white arsenic 
in sal soda, and is mixed with lime and water before it is used as a 
