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the true Sap of Trees is deposited during Winter . 
existence of vegetable circulation, which is denied by so many 
eminent naturalists. I have not, however, found in their writings 
a single fact to disprove its existence, nor any great weight in 
their arguments, except those drawn from two important errors 
in the admirable works of Hales and Du Hamel, which I have 
noticed in a former memoir. I shall therefore proceed to point 
out the channels, through which I conceive the circulating fluids 
to pass. 
When a seed is deposited in the ground, or otherwise exposed 
to a proper degree of heat and moisture, and exposure to air, 
water is absorbed by the cotyledons and the young radicle or 
root is emitted. At this period, and in every subsequent stage 
of the growth of the root, it increases in length by the addition 
of new parts to its apex, or point, and not by any general dis- 
tension of its vessels and fibres ; and the experiments of Bonnet 
and Du Hamel leave little grounds of doubt, but that the new 
matter which is added to the point of the root descends from the 
cotyledons. The first motion therefore of the fluids in plants is 
downwards, towards the point of the root; and the vessels 
which appear to carry them, are of the same kind with those 
which are subsequently found in the bark, where I have, on a 
former occasion, endeavoured to prove that they execute the 
same office. 
In the last spring I examined almost every day the progressive 
changes which take place in the radicle emitted by the horse ches- 
nut : I found it, at its first existence, and until it was some weeks 
old, to be incapable of absorbing coloured infusions, when its 
point was taken off, and I was totally unable to discover any 
alburnous tubes, through which the sap absorbed from the 
ground, in the subsequent growth of the tree, ascends : but 
O 2 
