7 
afterwards inserted in them, under the idea that there might be 
something congenial to the fruits in stocks of this kind. The 
grafts grew tolerably, and equally well in all ; but there was a 
want of hardness and elasticity in the wood, and at the end of 
three or four years all began to canker.” 
225 Apple-trees, Canker. “ The canker, however, which con- 
stitutes their most fatal disease, often arises from other causes. 
It is always found in those varieties which have been long in 
cultivation, and in these it annually becomes more destructive, 
and evidently arises from the age of the variety ; but it often 
appears to be hereditary. A gravelly or wet soil, a cold pre- 
ceding summer, or a high exposed situation, adds much to its 
virulence. It is most fatal to young free growing trees of old 
varieties, and I have often seen the strong shoots of these totally 
destroyed by it, when the old trees growing in the same orchard, 
and from which the grafts had been taken, were nearly free from 
the disease. The latter had ceased to grow larger, but con- 
tinued to bear well, not being of very old kinds of fruits; the 
young stocks, by affording the grafts a preternatural abundance 
of nourishment, seemed in this instance to have brought on the 
disease; and I have always found that transplanting, or a heavy 
crop of fruit, which checked the growth of the tree, diminished 
its disposition to canker. In middle-aged trees of very old 
kinds, a succession of young shoots is annually produced by the 
vigour of the stock, and destroyed again in the succeeding 
winter; the quantity of fruit these produce is in consequence 
very small. In this disease something more than a mere ex- 
tinction of vegetable life appears to take place. The internal 
bark bears marks of something similar to erosion, and this, I 
believed formerly to be the original seat of the disease ; but 
subsequent observation has satisfied me that the canker is a 
disease of the wood, and not of the bark. It does not appear 
to me to be ever a primary, or merely local disease, but to arise 
from the morbid habit of the plant, and to be incurable by any 
topical application.” 
226 Apple-trees, YOUNG SEEDLINGS NOT PROLIFIC. “Being sat- 
isfied, after much unsuccessful experience, that those varieties of 
the apple, of which the original trees had long perished from 
old age, could not be made to grow. I susjiected that grafts, 
taken from very young seedling trees, not yet in a bearing state, 
244. AUCTARIUM. 
