leat. 
1901 | GERMINATION OF SPORES 51 
for some other substances. The spores of Aspergillus flavus 
readily fly off from the surface of the drop, and such spores, 
falling on the cover glass beyond the limits of the medium, but 
of course moistened by the slight water of evaporation, gave at 
nt n 
van and at ans 
The salts of the heavy metals have generally caused a slight 
increase in the germination of Aspergillus, but in no case have 
they acted very strongly. 
A repetition of the experiments with nitric acid, CuSO,, 
Cu(NO,), and FeSO, were also made in flask cultures at con- 
nw 

a germination of 50 to 70 per cent. 

centrations ranging from ae ee Nitric acid of ee 
> 
and below has in every case given a small percentage of germina- 
tion. The spores thus germinated show a considerable length of 
germ tube. Iron has had a similar but weaker effect. So far 
as could be ascertained from flask cultures, the copper com- 
pounds have at most caused a swelling of the spore, and in 
isolated cases the very slight protusion of a tube. 
Although the stimulating action of the organic acids here 
included, as also the action of alcohol, may be a very different 
one from that of the inorganic acids, yet this stimulus of the 
Organic acids is in no case a very remarkable one. As to 
whether or not these organic substances act as peculiar stimuli, 
Or as food substances direct, there is evidently no good clue, for 
it is not yet possible to draw the line between those concentra- 
tions which should be considered stimulating or poisonous and 
those at which there may be an action merely as food. Clark’s 
nm, 
results previously mentioned have shown that alcohol at — is the 
lowest concentration at which any inhibition of the germination 
of Aspergillus in nutrient media occurred. 
In Seneral, the action of the organic acids as food sub- 
Stances has been determined by means of the corresponding 
salts, and further than this we know very little about them. 
72 
The stimulus given by Joo OF less of acetic acid to both fungi 
