ArsenicaIv Poisoning oe Fruit Trees. 9 
from another orchard and shows how the woody tissue is stained. 
The notch shows where a portion of the stump was removed for 
the purpose of examination. This tree was in bloom when dug 
up. It was perfectly representative of a number of other trees in 
the same orchard which had already been dug up or had been 
marked for removal. Many trees in this immediate neighborhood 
are affected in the same manner. The trouble is not confined to 
one orchard. In this case we found it in four, we might say, con¬ 
tiguous orchards. I have taken portions of at least 14 different 
trees. They were from a considerable variety of soils and were-trees 
that had just been removed or which we removed ourselves, or are 
still standing in the respective orchards. So far as I could learn, 
only two of these trees failed to show some life this season and one 
of these was a pear tree which we dug up ourselves. This tree had 
been cut back severely in 1907 and had thrown out a few shoots, some 
of which had made a fair growth. None of them were trees which 
had died and remained standing and had had an opportunity to 
absorb arsenic as dead trees. As stated, some of the trees repre¬ 
sented by our collection are still standing and were in full bloom at 
the time we removed the roots and branches. The condition of 
the roots and bark, however, was that produced by the long con¬ 
tinued action of the poison. 
The conditions found are as follows: The bark at the base 
of the trunk and just beneath the ground is destroyed and the 
damage extends up the trunk sometimes even into the limbs, (see 
plcite II.) This damage is shown on the trunk by the bark being 
brown and sunken. On the roots, the bark is disintregated as is 
well shown by Plate IV., Fig i, a sample taken and photographed 
by Mr. Whipple. Often, in the advanced stages of the trouble, 
the bark is almost charred and the wood itself is even blackened. 
The tissue is strongly attacked and yields to the rasp like wood 
charred sufficiently to destroy its fibre. It looks and acts like wood 
acted on by a dilute acid, sulfuric acid for instance, only the dark¬ 
ening is not, as a rule, so intense as would correspond to the same 
degree of disintegration by this acid. 
The limbs and branches of trees affected in this way usually, 
but not invariably, present a case of “black heart.” The interior 
portion of the branch is strongly discolored with a margin pro¬ 
nouncedly darker than the rest of the interior. (Plate IV., Fig. 2 ; 
also Plate III., Figs, i and 2). This condition is usually attributed 
to another cause, freezing at some time or other, but we have pretty 
direct proof that in these cases, it probably has been 
caused by the poisoning of the tree. It is a rule that branches of 
healthy trees show this difference to a very small extent, they be¬ 
ing usually white from the center to the circumference. Even in 
Fort Collins, where we have severe changes in the temperature. 
