16 LIFE OF A TREE, 
tain a number of fragments of wood, small broken 
pieces of the branches or leaves, or other parts 
of the tree. If we could examine it chemically, 
we should find yet more strikingly that it was 
nearly the same as wood in its composition. Per- 
haps then, it may be said, the young plant ob- 
tains its wood from the earth in which it grows? 
The following experiments will shew whether 
this conjecture is likely to be correct or not. 
Two hundred pounds of earth were dried in 
an oven, and afterwards put into a large earthen 
vessel: the earth was then moistened with rain- 
water, and, a willow-tree weighing five pounds 
was planted therein. During the space of five 
years, the earth was carefully watered with rain- 
water or pure water. ‘The willow grew and flou- 
rished; and, to prevent the earth from being 
mixed with fresh earth, or dirt being blown upon 
it by the winds, it was covered with a metal 
plate, full of very minute holes, which would ex- 
clude everything but air from getting access to 
the earth below it. After growing in the earth 
for five years, the tree was removed, and on 
being weighed was found to have gained one 
hundred and sixty-four pounds, as it now weigh- 
