XII 
ROM the artistic point of view 
trees have three characteristics 
which may be separately studied 
— form, texture, and color. 
The first element in the form of a tree is 
its general outline, its contour, the silhouette 
it makes when relieved against the sky or 
against masses of trees of other colors. The 
outline peculiar to a given species varies a 
good deal, of course, in different individuals ; 
but in all full-grown and well-grown indi- 
viduals it will be so nearly the same that the 
typical shape of the species may often be 
expressed in a very simple diagram on paper. 
An isosceles triangle with a broad base, for 
instance, gives the typical outline of the 
spruce ; a similar figure, but with swelling 
sides, gives that of a freely developed hem- 
lock ; the white elm would fill a vase-like 
figure supported by a straight line for the 
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