[ *35 ] 
they contained and preferved. Immediately after 
this, the bloifoms, flowers and fruits make their 
appearance. This is the ufual operation ; but in 
the cafe before us, nature was, as it were, fur- 
prized by art : what Are fhould not have done till 
fpring, fhe did in the winter, flecaufe the heat of 
the hot-houfe produced that expanflon,. which, 
according to the natural courfe, ought to have 
been effected by the rays of the fun darting lefs 
obliquely than before upon the horizon. There 
is no doubt but it is to heat, either natural or ar- 
tificial, that this expanflon is owing ; and the ex- 
periment proves that it is only in that part of the 
tree, which is expofed to the effedt of heat, 
that the fap, which in every other part remains 
torpid and inactive, is put into motion, and pro- 
duces vegetation. From this, it appears that the 
vegetable oeconomy is different from the animal, 
and that thole, who endeavoured to eftablifh the 
circulation in both, carried their analogy too far.. 
This faff, now eftablifhed, furnilhes a good 
reafon why in the tapping of the maple and fugar- 
birch-trees, fo much liquor runs out on one fide, 
and none at all on the other. It is well known 
that, if during the time of a froft, or a hummer’ s 
day, towards noon, you bore a hole on the fide 
of the maple-tree expofed to the foutb, you will 
get a great quantity of liquor from it ; and that 
if you bore the north-fide at the fame time,, you 
will not get a drop. The caufe of this evidently 
appears from what has been laid. One likewife fees 
why trees expofed to the fouth lofe a great; 
many of their branches, and fometimes die alto- 
gether, in the courfe of a fevere winter ; whilft. 
£ tree?. 
