120 OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 
greater or less extent, between the veins of the remainder of the 
leaf-blade, suffused yellow or red spots, which, when their 
centers die, have the appearance of reddish brown maculations 
surrounded with aureolae of red or yellow, аз the case may bei 
(PLATE 2, FIGURE I.) If instead of, or coexisting with, the 
spotting of the leaf we have a reddening or yellowing of the 
intervenium, the dead tissue forms strips. Marginal discolora- 
tion and death may occur, as in the adult leaves, but is not 
so frequent. 
In fully developed leaves the leaf-blade is not deformed. The 
tissue between the veins, and the margin, also, very largely, be- 
comes yellow or red, the discolored areas dying in time, the dead 
tissue assuming a color which ranges from fewille-morte to gray, 
according as the death has been rapid or slow. Instead, however, 
of beginning as a general discoloration of the intervenium, the 
disease may first appear as suffused greenish yellow spots, which, 
enlarging and becoming more definite in outline, often merge 
together, forming large maculations and stripes. These macu- 
lations and stripes may die to the edge of the healthy tissue | 
itself, but are more often surrounded by aureolae, which may be 
red, red and yellow, or yellow alone. (PLATE 1; PLATE 2.) 
The leaves near the base of the shoots sometimes show a slight 
variation from the characters just described. Ав soon as the 
spots appear between the veins, enlarge, and form stripes, the 
remainder of the parenchyma becomes chlorotic. Death in the 
diseased areas proceeds slowly and, when accomplished, the dead 
parts being soft and crumbly, the leaf is beaten by the winds 
into deeply incised fragments which hang together around the 
petiole. 
Diseased leaves—this remark is generally applicable—fall 
sooner or later with, or without, their petioles. The fall of the 
leaf prior to that of the petiole occurs, so far as I have been 
able to ascertain, only when the intervenium becomes diseased 
immediately around it. The death of the parenchyma then in- 
volves the death of the apex of the leaf-stalk, and the blade 
becomes severed from its support. 
“In the varieties of the grape-vine producing white fruit, the апгеоіе аге 
always yellow ; but in those bearing colored fruit they may be both yellow and 
red on the same leaf, the predominant color varying with the variety. 
