BULLETIN OF THE BUSSEY INSTITUTION. 7 
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Mr. Hersey’s idea as to the influence of climate in predisposing 
a plant to disease is presumably correct, for any marked change in 
the environment of an organism can hardly fail to bring about 
some change in its life processes, —a great or sudden change in 
the one causing a corresponding change in the other. All varie- 
ties of trees which have had the ‘‘ yellows” were formerly grown 
in a different climate (usually warmer) than that in which the 
disease has appeared. 
The introduction of plants or trees, like the peach and the nec- 
tarine, which are accustomed to a warm and equable climate, to 
one so changeable as that of Eastern North America, must inevit- 
ably result in physiological changes so great that in many instances 
a diseased condition is manifested. Some varieties would be 
disturbed more than others; also some individuals more than 
other individuals of the same variety. Still others, though slightly 
disturbed at first, might gradually recover their equilibrium, — 
that is to say, become acclimated. Only those individuals which 
could adapt themselves to their changed environment could sur- 
vive for any length of time. Such individuals we call ‘* hardy,” 
or refer to them as having more ‘‘ constitutional vigor,’’ — terms 
more or less vague, but nevertheless convenient until our knowl- 
edge of such characters becomes more accurate, — by which is 
meant that they inherit certain characters which tend to enable 
them to continue in their life-work and remain like their ancestors 
in spite of the vicissitudes of external change and the consequent 
inducement to variation. Such characters the White Magdalene 
Peach seems to have, and the question arises why have not more 
varieties of peaches become acclimated? In the first place, it 
would appear that since the importance of the idea above stated 
has not been generally recognized hitherto or clearly grasped, no 
special pains have been taken to put it in practice. Because of 
this inattention, it is not improbable that many a tree which had 
become fairly well acclimated has been ignorantly destroyed. 
Then, again, it is well known that the peach and some of its 
closely related species are not overburdened with those qualities 
included under the term ‘‘hardiness.” They have, as a rule, just 
the opposite qualities which collectively may be called ‘ tender.” 
This is shown in many ways, —one notable instance is that in 
spraying peach trees to repel the attacks of insects and fungi, 
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