Arsenical Poisoning of Fruit Trees. 
5 
the opinion that the effect of the alkali has been nothing more than to 
increase the action of the arsenic and has not been the cause of it. I 
am led to modify my views in regard to the importance of the part 
played by the alkalis because I have found cases of corrosion by arsenic 
under conditions which preclude their action. This in no way contra¬ 
dicts any facts established in regard to the adequacy of sodic chlorid 
or carbonate to bring arsenic in solution when present in the form of 
lead arsenate, calcic arsenite or as Paris green, but simply adds the 
fact that trees may be attacked in soils practically free from these salts, 
indicated collectively by the term alkalis. 
The result of my study of this subject during the past year has 
strengthened my conviction that the conclusions presented in Bulletin 
131 were not only fully justified by the facts presented, but were very 
conservative and I do not see any reason to modify any statement by 
making it less general or in any way milder. I have, furthermore, 
learned of no fact indicating any reason for altering the previous find¬ 
ings of Professors Paddock and Whipple. These gentlemen did their 
work thoroughly and with that conservatism demanded olf the really 
scientific worker. In the following pages we shall present some new facts 
but they will in the main be a re-presentation of the main points set 
forth in Bulletin iv 
1 
In the bulletin just referred to three phases of the question were 
set forth : First, the corrosive action of arsenic which had already col¬ 
lected about the crown of the tree, and designated as local irritant 
poisoning; Second, the action of the arsenic which had been taken 
into the system of the tree and designated as systemic poisoning; 
Third, the action of lime, showing that it probably exercised a toxic 
act ; on either alone or in conjunction with the arsenic. The possible 
action of both cooper and lead is freely admitted, but that of the arsenic 
is candidly considered as clearly the most important one and these two 
are scarcely more than mentioned for the purpose of admitting the 
possibility of their exercising some influence. 
The most striking effects upon the trees are produced by the cor¬ 
rosive action of the arsenic on the crown and roots, and this form of 
the trouble is the one which forces itself mostly upon the average 
man. 
Description of the Trees. 
The effect of the arsenic does not express itself in the appearance 
of the tree till its action has gone so far that the death of the tree is 
very near. The first general signs of trouble are an early ripening of 
the foliage the first year followed by heavy blooming and usually an 
abundant setting of fruit the second. This fruit is .seldom matured as 
the tree usually dies in late summer or early fall, the fruit and leaves 
remaining on the tree. In the case of pear trees, the foliage is mostly 
of a deep purple on the badly affected trees while that of healthier trees 
is still green. An examination of such trees reveals the following con- 
