OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 129 
addition of an iodine solution readily shows. (PLATE 3, FIGURE 
4.) This observation regarding the presence of starch in a few 
chloroplasts applies only to those cases where the prenecrotic 
coloring of the diseased tissues is red, but does not apply when 
the change of hue is not apparent or yellowish. In these cases 
the chloroplasts do not appear to contain starch, and their vacuo- 
lation is more pronounced, which fact would lead one to suspect 
that death does not really occur without some previous discolora- 
tion of the tissues, however transient it may be. 
When the death of the tissues is less rapid, vacuolation and 
distension of the chloroplasts is marked, and one will observe 
plasmodium-like aggregates here and there in the cells, but in 
more important masses at the lower extremities. With the final 
occlusion of the lumen all further changes are arrested. (PLATE 
3, FIGURES 3, 6; PLATE 4, FIGURES 3, 4, 5 ) 
When the cells die with moderate rapidity, 1. e., when the sec- 
tions are taken from typical diseased leaves, the vacuolation 
and plasmodium-like aggregation of the chloroplasts seems to 
reach a maximum. The homogeneous matter occluding the 
lumen, though still dense, is light-colored. 
As the rapidity of death still decreases, the tendency of the 
chloroplasts to run together is less marked; though still vacuo- 
late, they distend less and their resorption progresses further 
and further. The density of the deposit in the cells also 
decreases. (PLATE 4, FIGURE 5.) 
Finally we come to the stage (diseased leaves that become 
entirely chlorotic, the original diseased areas dying first and thus 
remaining distinct) when sections through an autumn leaf near 
its fall and a diseased leak ет not at at alb Ot Ver? little in 
appearance; traces of chloroplasts may remain in both cases, and 
the lumen may also be slightly occluded by homogeneous or gran- 
ular matter. (PLATE 3, FIGURE 2; PLATE 4, FIGURE 5.) 
The chloroplasts ар to the stage of plasmodium-like aggrega- 
tion stain readily, but as their resorption progresses further, 
they stain less readily and, in fact, at the final stage (autumn- 
leaf stage may I not call it?), they hold Ше acid fuchsin less 
readily—the other cell inclusions not at all—and decolorization 
in potassium bichromate is unnecessary. 
