434 BOTANICAL GAZETTE [JUNE 
the cells are killed by poisoning, without plasmolysis, both by’ 
the fungus itself and by very delicate solutions of oxalic acid, 
while with the stronger solutions obtained in mycelium extracts 
or made up directly with the acid the same effect is accompanied 
by plasmolysis. The softening and bleaching effect of the acid 
even in 0.01 per cent. solution was very evident to the naked 
eye. 
The production of gallic acid from tannin by the growth of 
Botrytis has been described above. Ina I per cent. solution of 
this substance a lettuce leaf petiole became softened and col- 
lapsed much as in the Botrytis extract, but more slowly. A 
dark color was produced much as in the extract, rather than the 
bleaching by oxalic acid. 
It seems to the writer that we have to seek in some such 
explanations as these the cause of the poisoning and death of 
the cells of tissues attacked by Botrytis. Most of those who 
have considered the subject before seem to have overlooked the 
fact previously stated that two distinct effects are brought about 
_ by the fungus, and that no one substance can produce both of 
these. That the first or poisonous substance is not an enzyme 
is plainly proven. That it is oxalic acid seems more than 
»ba le from the regular occurrence of this. substance and its 
ribed effects. The discoloration of the cell walls which the 
produces, rather than the bleaching brought about ae 
on of oxalic acid, is readily explained by the decomposi- — 
tannin or some similar compound. eo 
may now be considered briefly, in the light of this 
— 
e tendency in this species to require saprophytic nour: 
t preliminary to its parasitism. If spores of Botrytis are “ 
water upon living tissue no infection ordinarily — 
ae juice or any good nutrient be added, inf c on 
under the conditions previously enumerated. 
energy ot vigor, by such nourishmen'-— 
defnitely, the idea has been that the produc 
lose-dissol ing enzyme is” stimulated by this 
