TAXONOMIC CHARACTERS OF ALTERNARIA AND MACROSPORIUM 463 
of the fungi planted in one of the punctures. The cultures were kept 
with the plates inverted, without covers. In no case was there any- 
con tamination after the plates had been coated and very little occurred 
during the process. In the least humid atmosphere there appeared 
to be no change in the water content of the medium even after sixty 
days. 
In all cases where aerial mycelium was produced, there was an 
increase in its production in the saturated atmosphere over that under 
ordinary conditions. Those species producing the greatest abundance 
of mycelium produced proportionately fewer spores. On account of 
the presence of the paraffin film, the usual colony form was lacking. 
A. hrassicae var. microspora and M. sarcinaeforme, both of which pro- 
duced almost no aerial mycelium, produced an abundance of spores. 
At room humidity little mycelium was produced, and that was in 
tufts around the needle pricks. The relative production of spores was 
greater than in the saturated atmosphere; the submerged mycelium 
grew rapidly under the paraffin and covered the plate. In some cases 
the conidiophores ruptured the paraffin coat. This was true of M. 
sarcinaeforme to a greater extent than of any other species. In the 
very dry atmosphere no aerial mycelium and no spores were produced 
with the exception that M. sarcinaeforme produced a few spores in air 
bubbles in the paraffin coating. 
Reaction to Bacterial Influence 
One species of bacterium which will be designated as B. x, occasion- 
ally occurred as a contamination on plates. It had a marked in- 
hibitory action upon the growth of the fungi and was therefore used 
for special study. Plantings of all the species of fungi that were being 
studied were made in the usual way, then after four days the plates 
were inoculated on four sides at about i mm. from the outer edge of 
the colonies with cultures of B. coli, 2 strains, B. subtilis, and B. x. 
In all cases the fungi grew through the colonies of B. coli without 
showing any reaction. Occasionally in colonies of B. subtilis there 
was slight darkening of the mycelium. On the sides of the fungous 
colonies opposed to the colonies of B. x, however, there was in every 
case a marked reaction by the submerged mycelium. The hyphae were 
inhibited greatly m growth, were much darkened and extremely 
torulose. Nodules were produced along the hyphal threads and at the 
extremities of hyphal branches. The reaction by all the fungi was 
