280 Mr . Knight’s Account of some Experiments 
have ascertained by frequent experiment. The case was now 
different: much new bark and wood was generated on the 
lower lip of the wounds, become uppermost by the inverted 
position of the branches ; and I have no doubt but that the new 
matter, thus deposited, owed its formation to a portion of sap, 
which descended by gravitation, from the leaves growing between 
the wounded parts and the principal stems. 
The result of this experiment appears to point out one of the 
causes why perpendicular shoots grow with much greater vigour 
than others: they have probably a more perfect and more 
rapid circulation. 
The effects of motion on the circulation of the sap, and the 
consequent formation of wood, I was best able to ascertain by 
the following expedient. Early in the spring of 1801 , 1 selected 
a number of young seedling apple-trees, whose stems were 
about an inch in diameter, and whose height, between the roots 
and first branches, was between six and seven feet. These trees 
stood about eight feet from each other ; and, of course, a free 
passage for the wind to act on each tree was afforded. By 
means of stakes and bandages of hay, not so tightly bound 
as to impede the progress of any fluid within the trees, I nearly 
deprived the roots and lower parts of the stems, of several trees, 
of all motion, to the height of three feet from the ground, 
leaving the upper parts of the stems and branches in their 
natural state. In the succeeding summer, much new wood ac~ 
cumulated, in the parts which were kept in motion by the wind ; 
but the lower parts of the stems and roots increased very little 
in size. Removing the bandages from one of these trees in the 
following winter, I fixed a stake in the ground, about ten feet 
distant from the tree, on the east side of it ; and I attached the 
