CUCUMBER-TREE 
else, and so escape untavorable conditions. Thereis a natu- 
ral climatic belt to which the life of a forest is adjusted. In 
the present instance, as the favorable conditions near the 
poles were disturbed by the cooling influences of the glacier 
approaching from the north, the individual trees on that side 
of the forest belt gradually perished ; but at the same time 
that the favorable conditions of life were contracting on the 
north, they were expanding on the south, so that along the 
southern belt the trees could gradually advance into new 
territory, and so the whole forest belt move southward, fol- 
lowing the conditions favorable to its existence. It is there- 
fore easy to conceive how, with the slow advance of the gla- 
cial conditions from the north, the vegetation of Greenland 
and British America was transferred far down toward the 
torrid zone on both the Eastern and Western continent. 
Being thus transferred, the forest would be compelled to re- 
main there until the retreat of the ice began again to modify 
the conditions so as to compel a corresponding retreat of 
plants toward their original northern habitat. Thus it is that 
these descendants of the pre-glacial plants of Greenland, ar- 
rested in their northward march, have remained the character- 
istic flora of the latitudes near the glacial boundary.” 
CUCUMBER-TREE. MOUNTAIN MAGNOLIA 
Magnolia acuminata. 
Acuminata refers to the pointed apex of the leaves. 
Of two forms; in the forest it rises to the height of ninety feet 
with sturdy unbroken trunk for two-thirds its height; when allowed 
sufficient space to develop, it becomes a cone with branches that 
sweep the ground. Prefers a moist, fertile soil, but willegrow on 
rocky river-banks. Roots fleshy. Ranges from western New York 
to southern Illinois, south through central Kentucky and Tennessee 
to Alabama, and throughout Arkansas. 
Bark.—Brown, regularly furrowed and scaly. Branchlets slendery 
red brown, downy, later becoming gray. 
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