20 
Colorado Experiment Station 
roots, and may also destroy that of the trunk. It stains the woody 
fibre and causes its disintegration, sometimes producing a punky con¬ 
dition, and produces in the branches not so seriously affected a 
“black heart’’ condition. The lime arsenite and the lead arsenate pro¬ 
duce essentially the same condition in the tree but their action is very 
much less intense. 
Is Arsenic a Normal Constituent of Any Wood? 
I have not examined many woods for arsenic with the object of 
determining this point, one sample of oak and a few apple tiees. The 
oak contained no arsenic and I have found three apple trees in Colo¬ 
rado which were free from it, two of them were young trees and the 
third tree was one which had been killed by blight. Ti e presence 
of arsenic in fodders, vegetables, meats and even in the human body 
are matters which belong in the province of the toxicologist and. have 
but little bearing on a question dealing with such large quantities of 
arsenic as we do in studying its effect upon trees. I think that we 
are justified in assuming that normally arsenic is no more a part of 
an oak, an elm, or an apple tree than it is of the human body. In 
these days, however, when arsenic is spread broadcast upon our soils 
as superphosphates and arsenical sprays it would be rather surprising 
if it has not become so generally distributed that it might be. found 
in the organs and bones of almost any person. I am certain that 
should the writer of these lines die suddenly and his body be. sub¬ 
jected to a careful analysis, but little trouble would be met with in 
demonstrating the presence of arsenic in his liver, spleen, and possibly 
other organs,, of which facts I hope to give good proofs in a later par¬ 
agraph. " I think that we may waive the question of traces and as¬ 
sume without any fear of being in error that arsenic is not a normal 
constituent of apple and pear trees in the quantities with which we 
are dealing, from one half to upwards of 20 even to 34 parts of arsenic, 
calculated as arsenic acid per million of the woody tissue. 
Arsenic is Taken Up by the Trees. 
I have endeavored to convey to the reader a clear notion of the 
amounts of arsenic which have accumulated in our orchard soils. 
As much as 138 parts of arsenic, calculated as arsenic acid, having 
been found per million parts of soil. This does not mean that every 
man’s orchard roil is as rich as this nor does it necessarially follow that 
I could not have gotten samples from this orchard which would have 
run less, or perhaps more. This sample was a large one taken to 
the depth of one foot. I have shown that the water soluble arsenic 
in these soils in some cases exceeds 1.25 parts per million. The 
effects of soluble arsenical compounds on apple trees has also been 
shown. These cases were extreme ones, it is true, but they prove 
that apple trees may be killed by arsenic and they show the action of 
arsenic on the bark and wood of the tree. We will now give in 
