ON THE CAUSE OF DETERIORATION IN SOME OF 
-OUR NATIVE GRAPE-VINES, AND ONE OF THE 
PROBABLE REASONS WHY EUROPEAN 
NES HAVE SO GENERALLY 
FAILED WITH US. 
{Concluded from page 544.] 
BY C. Y. RILEY. 
Means or CONTAGION FROM ONE VINE TO ANOTHER.— The 
young lice, whether hatched upon the roots or in the galls, are 
quite active and crawl about for some time; and that they will 
spread from one vine to another, either under ground upon the 
roots or on the surface of the ground during the night, is highly 
probable. Such, however, cannot be the mode of spreading from 
one vineyard to another; for were it so, the malady could not 
possibly have assumed such proportions in so short a time as it 
has done abroad. One method of transport is upon the roots of 
seedlings and cuttings, but the insect cannot in this manner find 
its way to an old vineyard, and there must be still another means. 
Here we come to that part of the natural history of our louse 
which must assume the form of hypothesis until further observa- 
tions shall be made. In this country the malady is general, ar 7 
in France, where it is still spreading from one 
finds that it always commences at certain circumscribed pom 
and spreads from these points in more or less regu 27% 
There is no way of accounting for these nuclei— hese ante 
points in the centre of an old vineyard that never showed T 
the disease before, except on the hypothesis of the winged 1 
having flown there and started the colony- ; $ 
7 the root-inhab- 
iting type become winged. Why these individuals become 
while others never do, is, perhaps, not for us to unders 
noret ventures the Lamarckian suggestion that the ne 
i e reason, 
ting roots that are already destroyed may be on ‘chal rs 
pup are certainly found more particularly on badly 
All plant-lice multiply agamically during the § 
) 
E 
ed of quit- a 
