310 PHYLLOXERA VASTATRIX, OR 
tion. When the roots of the infected vines are 
examined it is easy to perceive that they have under- 
gone considerable change ; they are always soft and 
rotten, and their tissues, hypertrophied and void of 
firmness, yield to the pressure of the fingers. 
These serious disorders are due to a species of 
aphis, which has been named Phylloxera vastatrix. 
This insect, which is almost invisible to the naked eye, 
establishes itself upon the roots of the vine, and per- 
forates them with its proboscis in order to feed upon 
their juices. These repeated perforations probably 
irritate the tissues and induce hypertrophy. They 
give rise to knots upon the fibres of the roots, which 
are quite peculiar to the new disease, and form a funda- 
mental distinction between it and all other kinds of 
affections observed in the vine, such as the " pourridie" 
or " blanquet," a sort of rot produced by subterranean 
fungi, and the disease " camargue " which has already 
caused the destruction of a large number of vine 
plantations. It must at the same time be remarked 
that the Phylloxera never remain upon the roots which 
are beginning to decompose. When one part grows 
putrid they immediately remove to another. In fact, 
they cause putrefaction, always going before it, and 
never following after. 
Hitherto none of our own varieties of vine has 
escaped this new disease, but it is reported that 
there are some American varieties in the outskirts of 
Bordeaux, which, although they have been surrounded 
by infected plants for three years, show as yet no signs 
of suffering from the new disorder. The insect which 
thus riots on the vines belongs to the genus Phylloxera, 
and constitutes part of the order of Hemiptera, and 
