1899] TOXIC EFFECT OF DELETERIOUS AGENTS 385 
agent for tissues, and even more widely asa preservative. It 
inhibits germination in the mold spores used at an average con- 
nm RN ae 
centration of rae and is fatal to all except Penicillium in *. 
Five per cent. of the spores of Penicillium survived immersion in 
this concentration (17.6 per cent.) for 72 hours at 28° C. All, 
} ; 8 ; 
_ however, were killed by = which was the greatest concentra- 
tion required to kill in the case of any agent tested. 
| The presence of alcohol in “ and = concentration distinctly 
fetarded germination of Sterigmatocystis and Botrytis. No 
retardation was noticed with Aspergillus or GEdocephalum, The 
latter, indeed, showed some evidence of acceleration of germina- 
tion in = and = concentrations, but it was not sufficiently 
marked to be certainly stated. The stimulation of mycelial 
development and retardation of fruiting in ” was very marked 
with Aspergillus and Sterigmatocystis. Cdocephalum and Peni- 
tillium showed some stimulation of mycelial development and 
‘slight retardation of fruiting in this concentration. Botrytis 
Produced its heaviest mycelium in = and “ . 
_ The change that a plant may undergo as it grows older, 
‘lM the character of its election of foods is of great interest to 
Physiologists (Davenport ’99, p. 333). Duclaux (’89) found 
that while alcohol restrains or arrests germination in mold 
‘pores, it is made use of almost as abundantly as sugar by the 
/Mdult plant. My results would seem to support this view. It 
pay be possible, however, that alcohol acts as a stimulant rather 
Man as a food, as is the case with zinc sulfate, and other non- 
Nourishing compounds. Richards (’97) found that the addition 
0035 per cent. Zn SO, to aculture medium in which Aspergillus 
Meer Was growing doubled the dry weight of the mycelium. 008 
‘Pt cent. Zn SO , Similarly added to a flask culture of Botrytis 
“tsed a production of quadruple the normal weight of myce- 
fom, We cannot suppose that the small amount of zinc present 
