Arsenical Poisoning of Fruit Trees. 
27 
ly, corresponded to 34.5 parts of arsenic per million. We have stated 
that we find this corrosion of the bark in all stages of advancement 
from a mere film on the bark to a point where it has eaten through the 
bark and attacked the woody tissue and have'found 1 this woody tissue to 
contain arsenic equivalent to 13.20 parts arsenic acid per million. We 
have then this series of facts showing the progress of the disease till the 
girdling is complete, or so large a portion of the crown and roots have 
been destroyed that the tree dies. The amount of arsenic in the bark 
and in the tissues in extreme cases is as great as is found in tissues 
known to have been killed by arsenic but we do not know that the 
amount found in the destroyed root is not very many times the mini¬ 
mum amount necessary to produce this result. I have no hesitancy in 
concluding that arsenic applied to trees as arsenical sprays, i. e., as 
Paris green, as arsenite of lime (lime, sal soda and white arsenic), and 
as arsenate of lead has produced this trouble. 
Arsenic in the Trunk and Limbs. 
That I am unable to distinguish, in cases of trees which have 
died of irritant arsenical poisoning, how the arsenic found in the woody 
tissue was taken up is evident. The trees described were all in a dy¬ 
ing condition but not dead, therefore imbibition after death is out of the 
question, but whether the arsenic found had been taken up by the wood 
from the injured crown or had been gathered by the feeding roots 
from the soil I cannot tell. Since this is simply a matter of fact 
which cannot be directly observed, I will assume that both methods have 
played a part. That the roots gather arsenic from the soil will be 
abundantly proven and further that they may gather enough to injure 
or even kill the tree. On the other hand it is very probable that arsenic 
is absorbed directly from the corroded crowns and roots, in which case 
we would expect the tissues in the neighborhood of the wounds to be 
richer in arsenic than those parts farther removed. This is, I think 
as much as can be said in regard to this point. 
This is the case in these trees. We have in the woody tissue at 
the crown of a dying tree as much as 13.20 parts of arsenic, as arsenic 
acid, whereas in the limbs I have not found more than 3.28 parts per 
million and this was in a Bartlett pear tree which had be,en heavily 
sprayed, having received seven or eight sprayings annually for six 
years. The crown and roots of this tree were badly corroded and the 
roots contained 4.821 parts of arsenic acid per million. In a tree 
near which spray material had been mixed and which had killed the tree 
I found 8.32 parts per million in the roots and 6.35 parts per million in 
the limb. The roots and crown of this tree were badly corroded. 
This sample was taken in the month of March. I do not think that 
the tree would have put out any leaves if it had been allowed to stand. 
There is not always so marked a difference between the arsenic content 
of the crown and the limbs though a difference always exists; in the 
case O'f a pear tree, the one shown as a badly affected tree in Plate IV, 
the root showed 3.505 parts per million while the limbs gave 2.19 and 
2.64 parts per million. 
