least they ought not to be raised, with the exception of a vert? 
small number, by grafting. As nature renews them at each 
generation by means of Seeds, there exists a remarkable uni¬ 
formity in the shape, the taste, and the size, of their fruit, 
making allowances, however, for the difference resulting from 
the mixture of the impregnating substances they derive from 
each other, the variety of situations, of climate, and of soil. 
Although fruit trees are, in many respects, subject to the 
same laws as forest trees, yet, when the varieties of the 
former are distinguished by any very excellent produce, they 
ate proportionably sought after, and, with the view of re-pro¬ 
ducing them, recourse is then had to grafting. This is the 
reason, that among apples, the nonpareille, the golden pippin, 
and the pearmain, are so often to be met with ; and among 
pears, the colrnar, the bearre, and the chaumontel. Nature is so 
copious in all its productions, that probably there were never 
found any two of these varieties, or of any others, which were 
precisely the same, and that the difference observable among 
those of the same kind, is owing to the soil, the situation, and 
the trees themselves, which, in a few years, change in a great 
measure the peculiar characteristic of the fruit ;* they all in 
time become exhausted, they decay, and are attacked by the 
Canker. Now the following account is that in which, I think, 
that this disorder occasions the loss of fruit trees. 
As it is the property of heat to dilate bodies, and that of 
cold to contract them, it follows, that during the summer,; 
the channels of vegetable productions being expanded, the 
nourishing juices will freely circulate into them, and excite 
them to throw out shoots. On the contrary, in the winter, 
these channels, which were already too contracted, being 
drawn closer, they are disabled from performing their func¬ 
tions, the course of the sap is checked, and its passage being 
obstructed to the parts farthest from the trunk, where nature 
is least active, it is obliged to flow back into the parts which 
are nearest to it. This is the reason, that, in the first stage of 
this disorder, the extrenilties of the branches being deprived 
of nourishment, get slender, dry up, and die. If trees, when 
in this state, are transplanted into a better soil, and especially 
if the temperature is a few degrees warmer, they recover ; but 
the remedy which I have just recommended, concentrates for 
iK certain time, in the roots and trunk the nourishment which 
was intended to have made the top grow, which has been 
lopped off. The beneficial effect of this operation on the tree, 
is, that it acquires by it new vigour, that it supplies its former 
boughs with others stronger and better grown; and, lastly, 
that the sap being of a better quality, is more likely to con¬ 
vert itself into fruit. 
* There are commonly reckoned three varieties of the bearrey the grey, 
the red, and the green: Miller assures us, that he has often met with all 
three On the same bough. I am convinced, that an attentive observer 
might say as much of many other sorts, apples as well as pears. 
When 
