OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 137 
in the unripened portions the tissues will be altogether devoid of 
starch. In the discolored areas of the woody bundles, the com- 
ponents of the tissues are seen either to have their walls simply 
stained brown or else the cell cavity is partially or wholly filled 
up with a black brown deposit. . . . The larger ducts and vessels 
are often seen to be more or less filled up with thylles, which are 
developed sometimes to a great extent."! 
These observations are correct. Canes taken from diseased 
vines show a paucity of starch, and, when treated with 1 per cent. 
iodine solution, give (macroscopically) no starch reaction at all. 
In section taken through canes with immature spots, starch will 
usually be found under the microscope, generally in the matured 
tissues, though, contrary to Dowlen's observations, I have found 
it in the immature spots, and in larger quantity when suber is 
produced than when it is not. Its entire absence, however, І have 
also observed. Тһе presence or absence of starch in the cortex 
_ depends, I believe, on the production or nonproduction of the 
suber. The presence of starch in the xylem, ligneous medulla 
and pith near the protoxylem depends also, to a certain extent, 
on the production or nonproduction of the cork—the relation, 
however, is not so apparent. 
The presence, or absence, of starch also bears а very close 
relation to the quantity of brown granuloid, globoidal, or homo- 
geneous matter found in the diseased cells. The production of 
these homogeneous substances is proportional to the amount of 
starch present. Тһе freer the cells from occluding matters, the 
freer the sections from starch. 
In a cross-section of an immature spot one will observe, suber 
being present, the following condition of affairs: 
The pith cells encircling the protoxylem are full of starch or 
of starch and brown, more or less finely divided matter, which 
run together into a 
the cell lumen, the 
d there as clear 
re globoidal, or 
t, or encom- 
may become coarser, predominant, or even 
pseudo-homogeneous mass and entirely fill 
starch grains being perceptible only here an 
spots. In other cases the brown masses аге mo 
fill the space between the starch grains like a cemen 
— 
Viticultural Commissioners for 1889- 
1 Dowlen, E. Report of Board of State 
90, бо. 1800. 
