281 
One important factor, to a great extent, influences the efficacy 
of all American resistant vines as a suitable stock for vines, and 
that is: deep and thorough cultivation. On the vigour and the 
strength of their roots will depend their power to counteract the 
wasting effect of the sap-sucking insect, and of infusing life and 
energy into the scion, and unless the ground be deeply stirred, the 
roots will fail to grow with the same Inxuriance they show in easily 
penetrated soil; the standard of resistance will as a result be lowered 
and the graft will fail to receive the amount of sap required to 
produce and nourish a large crop. 
By standard of resistance is meant that scale adopted by viti- 
eulturists all the world over which determines the degree of resist- 
ance to Phylloxera possessed by vines. In that table, 20 represents 
the maximum degree of absolute resistance, while 0 represents its 
minimum. Thus the resisting power of the best Rupestris and Rip- 
aria is 19.50; that of some of the hybrids, such as Jacquez and 
Leonir, 11 to 12; and that of Chasselas, Aramon, Grenache is 0, or 
absolutely nil. 
The resistance expressed by the numbers 16 to 20 is sufficient 
for all soils; that expressed by 14 or 15 is sufficient, too, where deep, 
free, moist, loamy soils occur, where roots grow rapidly; while all 
vines possessing a degree of resistance under 13 shuuld be discarded 
as non-resistant stock. 
The following table, drawn up by Viala, shows the resistance 
of some of the best known vines :— 
Comparative Resistance to Phylloxera. 
Species (Wild Vines). Cultivated Vines and Hybrids. 
Vitis Rotundifolia ( Eyeeey Gloire de aimee sca 
nong ) se dQ aria) 18 
Vitis Rupestris (Rock or Rupestris Martin Se 18 
Sand Grape) 5 .. 18 | Rupestris Monticola (du Lot) 18 
Vitis Riparia (River Bank Rupestris Metallica .. 16 
Grape) mi F .. 18 + Solonis Si ve .. 14 
Vitis Berlandieri #5 exes Fo Lenoir = te one. Ds 
Vitis Aistivalis (Summer Isabella 33 iD 
Grape) ° 16 
Vitis Labrusca (Fox Grape) 5 
Vitis Californica .. 4 
Vitis Vinifera ( European 
Grape) ae oe za 0 
A readily visible external indication of the degree of resistance 
to the attacks of the insect is afforded by nodosities and by tuber- 
osities on’ the root. The “nodosity” is a swelling on the tender root- 
lets of the grape vine. which is caused by the bite of the Phylloxera. 
All vines attacked by the Phylloxera show more or less these nodosi- 
ties, which are the result of local irritations. When these nodosities, 
however, assume a more pronounced appearance, such as deeply- 
