s8i 
on the Desce?it of the Sap in Trees. 
tree to the stake, at the height of six feet, by means of a slender 
pole about twelve feet long ; thus leaving the tree at liberty to 
move towards the north and south, or, more properly, in the 
segment of a circle, of which the pole formed a radius ; but in 
no other direction. Thus circumstanced, the diameter of the 
tree from north to south, in that part of its stem which was 
most exercised by the wind, exceeded that in the opposite di- 
rection, in the following autumn, in the proportion of thirteen 
to eleven. 
These results appear to open an extensive and interesting field 
to our observation, where we shall find much to admire, in the 
means which nature employs to adapt the forms of its vegetable 
productions to every situation in which art or accident may 
deposit them. If a tree be placed in a high and exposed situa- 
tion, where it is much kept in motion by winds, the new matter 
which it generates will be deposited chiefly in the roots and 
lower parts of the trunk ; and the diameter of the latter will 
diminish rapidly in its ascent. The progress of the ascending 
sap will of course be impeded ; and it will thence cause lateral 
branches to be produced, or will pass into those already existing. 
The forms of such branches will be similar to that of the trunk ; 
and the growth of the insulated tree on the mountain will be, 
as we always find it, low and sturdy, and well calculated to 
resist the heavy gales to which its situation constantly ex- 
poses it. 
Let another tree of the same kind be surrounded, whilst 
young, by others, and it will assume a very different form. It 
will now be deprived of a part of its motion, and another cause 
will operate : the leaves on the lateral branches will be partly 
deprived of light, and, as I have remarked in the last Paper I 
