OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 131 
that the decomposition of the chloroplasts is in inverse ratio to the 
density of the occluding matter, precludes the assumption that, 
in the major cases, these bodies act as nuclei of condensation, like 
crystals in supersaturated solutions. But if the chloroplasts play 
no part in the formation of the homogeneous matter, or its homo- 
logues, whence does it come? The answer to this question in- 
volves considerable difficulties, and must, at best, be largely 
hypothetical. 
The deposits in the lumen of the cells are probably genetically 
related, though it would appear, from their variation in form, 
that their ultimate composition is somewhat different. They all 
behave very similarly to reagents and stains. They dissolve in 
Javelle water, but are not at all, or but little, affected by either 
hydrochloric or sulphuric acid. А concentrated solution of potash 
has practically no effect on the homogeneous and granular 
matters, but will sometimes remove the globules in the epidermis. 
Fixing diseased tissues in Flemming’s solution is apt to make the 
homogeneous, granular, and globoidal matters so dark that, for 
staining purposes, sections taken from such material are very 
imperfect. Chromic acid, one per cent. solution, does not change 
the color of the cell occlusions to any extent, and sections taken 
from material fixed in it are hardly more opaque than those taken 
from alcoholic material. 
The deposits in the cells turn black when the sections are 
placed in a saturated solution of iron acetate; the black color 
Flemming’s solution imparts to them may be very largely removed 
by peroxide of hydrogen. 
Amongst the stains, iron haematoxylin’ is retained vigorously 
by the deposits, but Bóhmer's haematoxylin is without effect. 
“Тһе homogeneous matter colors deep red in safranin, takes eosin 
readily, colors in erythrosin, tropaeoline oo, carmalum, rosaniline? 
(dull red), orcein and hydrochloric acid. 
From these reactions of the deposits it is clear that they con- 
tain tannin (action of iron acetate, regeneration of osmic acid by 
*I mordanted the sections in "liquor ferri sulfurici oxidati,” diluted with 
two volumes of water, for twenty-four hours; stained in 1 per cen 
of hematoxylin (Benda's) and differentiated in 20 per cent. ace 
* An alcoholic solution of equal parts fuchsin and methyl violet. 
t. solution 
tic acid. 
