t aside the tree-doctor to
his separate duties, just as the physician and the veterinary surgeon
already find their own distinctive spheres of work. The apparatus
required for the thorough eradication of disease in fruit trees will
be too expensive for the average grower to find any advantage in
buying it for use only a few times during the year; but the
tree-doctor, with his gangs of men, will be able to keep his special
appliances at work nearly all the year round.

For the destruction of almost all classes of fruit-pests, the only
really complete method now in sight is the application of a poisonous
gas, such as hydrocyanic acid, which is retained by means of a
gas-proof tent pitched around each tree. No kind of a spray or wash
can penetrate between bark and stem or into the cavities on fruit so
well as a gaseous insecticide which permeates the whole of the air
within the included space. But the gas-tight tent system of fumigation
is as yet only in its infancy, and its growth and development will
greatly help to place the fruit-growing industry on a new basis, and
to bring the best kinds of fruit within the reach of the middle
classes, the artisans, and ultimately even the very poor. Just as
wheaten bread from being a luxury reserved for the rich has become the
staple of food for all grades of society, so fruits which are now
commonly regarded as an indulgence, although a very desirable addition
to the food of the well-to-do, must, in a short time, become
practically a necessity to the great mass of the people generally.

The waste of effort and of wealth involved in planting trees and
assiduously cultivating the soil for the growth of poor crops
decimated by disease is the prime cause of the dearness of fruit. If,
therefore, it be true that the fruit diet is one which is destined to
greatly improve the average health of civilised mankind, it is obvious
that the tree-doctor will act indirectly as the physician for human
ailments. When this fact has been fully realised the public estimation
in which economic entomology and kindred sciences are held will rise
very appreciably, and the capital invested in complete apparatus for
fighting disease in tree life will be enormously increased.

Very long tents, capable of covering not merely one tree each, but of
including continuous rows stretching perhaps from end to end of a
large orchard, will become practically essential for up-to-date
fruit-culture. An elongated tent