1899] TOXIC EFFECT OF DELETERIOUS AGENTS 399 
Diagrams IX and X are simply a graphic representation of 
the more important features of this table. The values of the 
abscisse in each case =z in the expression 
of a normal 
2048 
solution. 
SUMMARY. 
rious agents than the higher plants. In the case of the mineral 
acids a concentration of from two to four hundred times the 
"strength fatal to the higher plants is required to inhibit the 
germination of mold spores under favorable conditions. 
2. Different species of fungi present great differences of 
tesistance to many agents. Of the agents tested in this-study, 
NiSO, permitted the greatest specific variation and dichloracetic 
acid the least. 
3. Particular forms of the same species present very different 
powers of resistance, depending probably on previous environ- 
ment. 
4. Individual spores taken from the same pure culture often 
Present considerable variation in resistance. 
5. The five forms used were found to be increasingly resistant 
to the toxic action of acids in the following order: Cédo- 
fephalum, Botrytis, Penicillium, Aspergillus, and Sterigmato- 
| ¢ystis. 
tum, Sterigmatocystis, Aspergillus. 
7. GEdocephalum and Botrytis, although on the average the 
Most susceptible to the various agents, have great specific PESES: 
“ices to certain agents. See FeSQ,, KI, and alcohol. 
8. Tests made with media not well suited for the normal 
development of the fungi tested will give a correct value for he 
: ling concentration, but the data regarding the point of inhibition 
*f germination are not of value. 
_ 9. Tests of the toxic value of solutions are unreliable when 
‘Made in hanging-drop cultures where water was used in the 
I, Fungi are in general much more resistant to most delete- 
i 6. Toward all the agents tested they proved increasingly 
_ Tesistant in the following order: Botrytis, Edocephalum, Penicil-, 
r 
