122 THE INSECT WORLD. 
- found in Paris, in the garden of the Ecole de Pharmacie. It had 
become common in 1822 in the departments of the Seine, the 
Somme, and the Aisne. In 1827, its presence in Belgium was 
announced. 
The apple-tree aphis, according to M. Blot, can only exist on 
that tree. Carried away and placed on any other, it very soon 
perishes. It does not attack the blossom, the fruit, nor the 
leaves, but fixes itself on the lower part of the trunk, whence it 
propagates itself downwards as far as the roots, underneath the 
graftings, &e. It also likes to lodge in cracks of the trunk and 
large branches. But it always looks out for a southern, and 
avoids a northern aspect. It is not active, walks very little, and 
its dissemination from one place to another can only be explained 
by the facility with which so small an insect can be transported 
by the wind, its lightness being still more increased by the down 
which covers it. 
The Myzoxyle mali renders the wood knotty, dry, hard, brittle, 
and brings on rapidly all the symptoms which characterize old age 
and decay in attacked trees. M. Blot recommends the following 
means for preserving the apple-trees from this insect: Employ 
for the seed-beds the pips of bitter apples only; give to the 
nursery and to the plants only as much shelter as is absolutely 
necessary ; avoid those sites which are too low and too damp; 
encourage the circulation of air, and the desiccation of the soil ; 
surround the foot of each apple-tree with a mixture of soot or of 
tobacco and fine sand. 
As for the manner of freeing a tree once invaded by this insect, 
the most simple plan is to rub the trunk and the branches, in 
order to crush the insects, or to employ a brush or broom. 
We spoke above of the reproduction of the aphis, but without 
entering into any particular details; we will now touch upon this — 
question, one of the most interesting in natural history. 
It was at the time when Réaumur was writing his immortal. 
‘Histoire des Insectes,” when Trembley was publishing his 
admirable researches on the freshwater Hydra, whose prodigious 
vitality we have mentioned in our work on Zoophytes and 
Molluses,* that another naturalist astonished the learned world 
~* “The Ocean World.” London: Chapman and Hall, 1868.—Ep. 
