OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 119 
identified except in the “all together.” Concretely : a vine show- 
ing but a single symptom of the California vine disease is, in 
itself, a doubtful subject. 
Symptomatology 
(а) Leaves.—The young leaves—on upper third of shoots— 
generally show particular characters only in the case of the chronic 
form of the California vine disease. When a vine is affected 
apoplectically they either remain normal or assume the characters 
common to the older and adult leaves or, when the shoots are 
defoliated without death ensuing, form a healthy plume, as it 
were, at their tips. In the apoplectic form the young leaves are 
not indicative, but in the chronic form they are very often pre- 
monitory symptoms; the vine first showing them may become no 
further diseased, but it is practically certain that other vines in 
the vineyard, if they are all of one variety and age, will, and 
not only lightly, but severely. The characters shown by the 
young leaves are, in the case of the chronic form, then of con- 
siderable interest. 
They are: 
Case r——The leaves become pale in the intervenium, growth 
ceases at the periphery— sometimes also between the veins— 
and death ensues. Тһе tissues not immediately affected, not 
having reached complete development, continue growing, the 
leaves becoming paler in color, more or less convex, and, accord- 
ing to the amount of dead tissue other than peripheral, variously 
distorted. (PLATE I, FIGURES 1, 2, 3, 4.) 
Case 2—The leaves, leaves more developed than those just 
described but of the same coloring, do not become convex as а 
Whole, but only in one or both wings of the petiolary sinus. This 
distortion is accompanied by a sinking of the tissues between the 
venation, and subsequent death. 
n older leaves the symptoms of the disease are variable and 
Cannot be accounted for by their position in regard to other 
diseased leaves. Those leaves that are still in fairly active growth 
may show the characters common to the young leaves described in 
Case 2. In other cases, and coincident with the furrowing and 
death of the wings of the petiolary sinus, there appear, to a 
