128 OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 
We found that the leaf dies in spots or stripes, infrequently 
without prenecrotic coloration, the rule being a reddening or 
yellowing before death, even though all the stages are concurrent 
as it were; we found that exceptionally the disease appears as 
yellow maculations, isolated or running together, when death is 
slow and confined to the diseased areas, even though the leaf 
turns chlorotic—but I did not lay particular stress upon the point 
that when death is very rapid, the dead tissue has a somewhat 
glossy brick tint, that when less rapid it is more reddish brown 
and matte and when slow, fawn-colored. These differences in 
coloration of the dead tissue have, however, considerable anatom- 
ical importance. 
If one examines sections through material showing the color 
characters mentioned above, he will obtain a conspectus of the 
behavior of the chloroplasts. Thin sections must be cut, owing 
to the opacity of the deposit in the lumen of the cells, when the 
chloroplasts may be well brought out by acid fuchsin,—carbol 
fuchsin and iron haematoxylin (the first gives the clearer 
preparations) do not give as sharp a differentiation. Acid fuchsin 
might almost be called a specific chloroplastid stain. Sections 
placed in it for a few minutes, and then washed in bichromate | | 
will show the chloroplasts deep red, the cytoplasm very faint ` — 
rose, the other cell inclusions being practically colorless. ВУ | 
means of this stain the chloroplasts may be studied without fear 
of misinterpretation. Carbol fuchsin and iron haematoxylin, 
the latter especially, did not appear to me quite so trustworthy ` 
and were soon discarded. 
If we take, then, a series of sections through diseased tissues , 
that have died with various rapidities and stain them, preferably | S 
in acid fuchsin, we shall find that the resorption, vacuolation 
and plasmodium-like aggregation of the chloroplastids is, 10 4 E 
certain extent, inversely proportional to the amount of lumes 
occlusion. In the tissues that have died very rapidly the deposit 
is homogeneous, dense, and the chloroplasts hardly show more 
than a slight vacuolation and some appear, in optical section, 
as hollow elliptical spheres; their center is not a vacuole, how 
ever, but a starch grain, as the blue color they assume оп 
А А еа де А IRR E В, 
