stance to the phylloxera, root and graft almost as easily as
St. George, and are quite sufficiently vigorous to support any variety
of vinifera. The former is more suited to the moister soils and
wherever there is danger of root-rot, and the latter to the drier
soils. In general, they are suited to a larger variety of soils and
condition than perhaps any other varieties.

"Riparia gloire should be planted only on rich, deep alluvial soil
containing an abundance of plant food and humus, what would be called
good garden land, such as river bank soil not liable to overflow.

"In most other soils Riparia x Rupestris 3306 is to be recommended,
except those that are rather dry, where 3309 is to be preferred, or
those which are very wet, where Solonis x Riparia 1616 is surer to
give good results."

The value of a species or variety for a resistant stock may be judged
somewhat by the visible effect of the phylloxera on the roots of the
vines. On susceptible species, the punctures of the insects rapidly
produce swellings which vary in size and number in accordance with
resistance of the species. Technically, the first swelling on the
young tender rootlets of the vine is called a nodosity. The presence
of a few nodosities on the root system does not indicate that a vine
is not a valuable resistant stock. When the nodosity begins to decay
and becomes of a cancerous nature, it is called a tuberosity. These
tuberosities decay more or less rapidly and deeply, and when they rot
deeply cause enfeeblement or death to the vine. Thus, on Vinifera
varieties the tuberosities are several times larger and decay sets in
much more quickly than on American species which show these
tuberosities. Ratings as to resistance of species are usually made
from the size and number of the tuberosities, though when these are
found producing a scab-like wound which scales off, there may be high
resisting power.

In order to convey with some degree of definiteness the power of
resistance to phylloxera, an arbitrary scale has been agreed on by
viticulturists. In this scale, maximum resistance is indicated by 20
and minimum by 0. Thus, the resisting power of a good Vulpina is put
as 19.5 and that of a poor Vinifera variety as 0.

ADAPTATIONS OF RESISTANT STOCKS TO SOILS AND CLIMATES

Resistance, of course, counts for naught in a stock which comes from a
species unsuited to the soil and climate or other circumstances of the
locality in which the vineyar