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OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 133 
retention of methylene blue seems to be due to the presence of 
tannin. 
In my observations, just described, on the anatomy of diseased 
leaves, I never mentioned that hyphae, plasmodia, and bacteria 
were always absent from pathognomonic tissues: such, however, 
is the case. In diseased tissues that have not been weathering 
under conditions favorable to the growth of fungi or bacteria no 
foreign organism of any kind is to be found. I must, therefore, 
deny the existence of Plasmodiophora californica, but in so doing 
I wish to impugn only the interpretation of Viala and Sauvageau, 
not the correctness of their observations. The facts exist as 
they saw them, but not as they interpreted them. 
CaxEs.— The anatomy of the shoots of diseased vines does not 
reveal any facts of importance until they begin to mature. Their 
maturation is somewhat fantastic and the resulting canes appear 
interspersed with green immature tissue. This immature tissue 
constitutes the immature spots so characteristic of the California 
vine disease and will, therefore, occupy our attention almost ex- 
clusively in the following remarks. 
I think it well, for clearness sake, to preface my observations on 
the immature spot with a brief description of a healthy cane, as 
seen in cross-section. We find, around the pith, a ring of w 
composed of wood-fibers and large vessels interspersed radially, 
at equal intervals, by the ligneous medulla; beyond the wood, 
the cortex, corresponding to the wood fascicles, Ше basts 
containing two to three or four rows of fibrous bundles and 
separated by a parenchymatous and widening prolongation of 
the medulla; beyond the bast, and separating it from the remain- 
ing cortical tissues, the suber; beyond the suber, and capping the 
basts, as it were, the pericycles; the other tissues, parenchyma, 
collenchyma, and epidermis, have turned brown, and have more 
or less collapsed. 
In immature spots the departure from t Е 
sketched it, is as striking as unexpected. Around the pith we 
find the ring of wood to be of unequal, instead of equal, diameter, 
and the wood fascicles to be of unequal development: at the 
center, or to one side of the center, in the i 
he normal, as I have 
mmature spot, they 
