the Ascent of the Sap in Trees. 341 
remained, in form and substance, similar to the small fruit-stalk 
attached to it. 
I was long at a loss to conjecture by what means nutrition 
was conveyed to the seeds of the apple and pear ; for I had rea- 
son to believe that it was not done by the medulla ; and I had 
previously ascertained that the seeds would derive nourishment 
from the pulp, when the fruit was taken prematurely from the 
tree. At length, in a large apple, which was just beginning to 
decay, I found a number of minute vessels, leading from the 
pulp to the tubes which originally constituted the lower parts 
of the pistilla, and to which the seeds are attached. These now 
appeared to me evidently to be the channels of nutrition to the 
seeds ; and, since I have known what I have to look for, I find 
these vessels sufficiently visible in every apple : there are, how- 
ever, five other tubes, which pass along the external edges of 
the cells of the core, to which I do not venture to assign an 
office. It appears to me not very improbable, that the internal 
organization of this fruit will be found to bear some resemblance 
to the placenta and umbilical cord of the animal economy. If 
transverse and longitudinal sections of young apples and pears 
be made, soon after the blossom has fallen, the pulp will appear 
to be of two kinds ; one of which is included within the vessels 
which carry up coloured infusions ; and this seems to be formed 
by continuation of the vessels and fibres within the wood. The 
other part appears to belong, in a great measure, to the bark : 
it is in very small quantity in the very young fruit ; but, at its 
maturity, it constitutes much the greater part of the pulp. The 
vessels, however, which diverge into the external pulp, and pro- 
bably convey nourishment tp it, appear to be continuations of 
the central vessels, every where, I believe, accompanied, as in 
