Arsenical Poisoning of Fruit Trees. 
4i 
only one of them has been found to contain more than five parts arsenic 
acid per million. 
In regard to the solubility of the arsenic in the orchard soils, 
I have shown that as much as 1.26 and 1.34 parts of arsenic acid 
per million of soil is soluble in water. The virgin soils on the other 
hand yield only traces or none. In this connection it is to be re¬ 
membered that the roots of the trees may be much more effective in 
bringing the arsenic into solution than distilled water. 
This bleeding takes place from cracks in the bark and also from 
old wounds made in trimming and is especially noticeable in wounds 
already one year old. I have watched this taking place, when the 
juices were, issuing through the medulla while no other portion of 
the section seemed to be taking any part in the process. It is com¬ 
mon to find this section of a wound surrounded by this deposit which is 
rich in lime and arsenic. The medullary tract seems to be the easiest 
channel for these juices to traverse, which may itself be an indication 
of a diseased condition. Prof. Longyear has suggested that the ducts 
whose function it is to conduct the sap of the tree upward, may be 
so clogged and the resistance offered to the upward diffusion of the 
sap so gre,at, that it follows this unusual course. The Professor 
kindlv consented to examine sections of affected trees and gives me 
the following statement of his findings: 
“Three lengths of affected branches, two inches in diameter, 
in which an outer layer about one-fourth of an inch thick of healthy 
sapwood remained, were brought to me in a fresh condition in 
February, 1910. 
“Transverse sections from different portions of these branches 
under the microscope showed the ducts in the uncolored sapwood free 
from obstruction and the cells of the medullary rays stored with starch. 
In the most highly colored zone, just between the healthy and the 
affected wood‘s the ducts were found to be filled with a yellowish or 
brownish gummy substance, insoluble in cold water and dilute solution 
of caustic potash. Toward the center of the branch this gummy 
material diminished in quantity quite rapidly but was not entirely lack¬ 
ing. In the colored area the medullary ray cells still contained in 
some instances a little starch but in most cases they were partly filled 
with brownish granules and globules of substances remaining or arising 
from the disorganization of the cell contents. It is evidently 
from these sells that the gummy matter has found its way into the 
ducts. This is shown by the fact that this material appears in a 
duct first on the side next to the, nearest medullary ray cells.“ 
In regard to the varieties affected I have seen this bleeding 
in the Jonathan more often than in any other, but it is not confined 
to this variety. I have also seen it in the Missouri Pippin, in the 
Spitzenberg and other varieties. 
The facts seem to me to point to the action of arsenic in con¬ 
junction with lime rather than to the action of either alone as the 
cause of this trouble. 
