122 OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 
very disordered further up. Or again, lignification may be im- 
perfect only around a few nodes, the internodes showing appar- 
ently normal maturation, and conversely. 
If one cuts a smooth cross-section of a shoot or cane that is 
bearing diseased foliage, or has been defoliated, he will notice that 
the wood is slightly discolored. The pith is best seen in longi- 
tudinal section; it will be found discolored more or less discon- 
tinuously, or turned completely brown, if the foliage has fallen. 
(d) SPURS, ARMS, AND TRUNK.—Externally, the spurs, arms, 
and trunk have the same appearance in diseased as in healthy 
vines. This is no longer true when cross-sections are examined. 
In the spurs the woody tissue of the previous year is discolored 
and, often, more especially near the edge, zoned with darker lines. 
In the arms the zones become less marked, and disappear before 
reaching the trunk. The discoloration of the wood is much more 
persistent, but hardly descends to the roots. 
Besides the characters just mentioned, the arms and trunk may 
show alterations due to die-back from old wounds, decay, and 
various other injuries interfering with the circulation. The 
tissues surrounding these impediments are generally affected in 
such a manner that their differentiation from those that have 
become diseased through the action of the California vine disease 
is impossible. The characters found in the arms and trunk, in 
the case of the California vine disease, are, therefore, of but 
very little diagnostic value, and, I am inclined to think, hardly 
worth the pains one must be at to find them. 
(е) Roors.—The roots do not present any characteristic altera- 
tions. They are either diseased, or not diseased, according to the 
situation in which the affected vines are growing and the presence, 
or absence, of root parasites, either animal or vegetable. If the 
affected vines are suffering also from the Phylloxera Vastatrix, 
Adoxus Vitis larvae, or nematode worms, the roots will appear 
damaged; they may be decomposed by root-rot (Dematophora 
Necatrix), or dry-rot, simply die, or, а frequent occurrence, be 
entirely sound. 
