14 
PLANTS. 
because, its rarefying power then ceasing, the greatly 
rarefied sap, and air mixed with it, will condense, 
and take up less room than they did, and the dew 
and rain will then be strongly imbibed by the leaves ; 
whereby the body and branches of the vegetable, 
which have been much exhausted by the great eva- 
poration of the day, may at night imbibe sap and 
dew from the leaves ; for, by several experiments, 
plants were found to increase considerably in weight, 
in dewy and moist nights. And, by other experi- 
ments on the vine, it was found that the trunk and 
branches of vines were always in an imbibing state, 
caused by the great perspiration of the leaves, ex- 
cept in the bleeding season ; but when at night that 
perspiring power ceases, then the contrary imbibing 
power will prevail, and draw the sap and dew from 
the leaves, as well as moisture from the roots. 
“ The instance of the ilex grafted upon the 
English oak, seems to afford a very considerable ar- 
gument against a circulation. For if there were a 
free uniform circulation of the sap through the oak 
and ilex, why should the leaves of the oak fall in 
winter, and not those of the ilex ?” 
These arguments, founded on many well con- 
ducted experiments, are strongly against the theory 
of an uniform circulation of the sap in vegetables, 
through different vessels, in the same manner as 
takes place in the animal ceconomy ; but that this 
matter may be cleared up as much as possible, we 
shall add the following decisive experiment, made 
by M. Mustel of the Academy of Sciences at Rouen. 
