199] TOXIC EFFECT OF DELETERIOUS AGENTS 319 
therefore to be attributed almost wholly to the un-ionized mole- 
a 
ail, CH, COOH, which proves to have a toxic value of 2.8.H. 
Penicillium showed a marked specific resistance to this acid, 
requiring ; for 48 hours to kill. This observation was accepted 
‘mily after repeated trials. Sterigmatocystis, so resistant to the 
16 
Dotrytis was particularly susceptible, being killed by ee which 
mineral acids, succumbed to —, and - inhibited germination. 
8 but one eighth the strength of HCl required for the same 
result, Although so much more fatal to Sterigmatocystis and 
Botrytis, germination and early mycelial development was much 
less retarded than with the mineral acids; so retarded the 
mination of CEdocephalum, but in the other forms this con- 
“aration had little effect. 
That acetic acid should prove so much more toxic to fungi than 
fe mineral acids was not anticipated (Migula’g90). Heald (96) 
und that it had but one eighth the toxic value of i on Zea, and 
"te fourth on Pisum. Kahlenberg and True (’96) found about the 
“me relation with Lupinus. The great variation in protoplasmic 
Stance to this acid is well shown by the following data: the 
Mar eel, Rhabditis aceti, thrives in a — solution, which is the 
. 2 
os ‘oncentration for Penicillium. Aspergillus spores are killed | 
qn 
4 j) those of Sterigmatocystis and CEdocephalum by “zs and 
ee of Botrytis by ~, jis fatal to Zea, and _” to Pisum. 
. 6 200 1600 
— a interest to note in this connection that not only ge 
la to be expected between different penne 2 
Same nce to deleterious agents, but different indivi png 
St pow, “pg =a even of the same species may have very ‘ ae 
irvamect, resistance, depending largely no doubt on Pr® itive 
Ned; - Pfeffer (95) grew Aspergillus on a nutri 
ining 8 per cent. dextrose and 1 per cent. acetic 
oo t 
) “td found that the fungus assimilated a far larger — 
