Be 
et 
CHROMOGENIC FUNGI WHICH DISCOLOR woop. 105 
and that of Thom * have shown that even when the form 
characters of two forms of Penicillium are alike, there 
may be distinct differences in the color of the fungus on 
certain different kinds of media. The former has made a 
revision of the genus Penicillium, based chiefly on physio- 
logical characters, but also taking into consideration the 
strictly morphological. The latter in studying the species 
of Penicillium which were found concerned in the ripen- 
ing of the various kinds of cheese found great difficulty in 
naming them, owing to the fact that what may be mor- 
phologically the same species may not have the same effect 
on the chemical properties of freshly made cheese, owing 
to varying action of different strains or races of Penicillium 
on the organic compounds present. 
Penicillium aureum Corda. 
Of the two species of Penicillium studied, the most 
common was identified finally as Penicillium aureum Corda. 
It is dimorphous, as has already been mentioned, and is 
one of the common species found on pine wood. It was 
also found in cultures from gum, oak, and other woods. 
A culture sent to Mrs. Flora Patterson was identified as 
P. aureum, thus verifying our observation. 
This species grows readily on the fresh sapwood of our 
most common forest trees, upon bouillon, and various 
vegetable decoction agar media, upon potato, starch, and 
other similar substances. The following cultural characters 
are taken from both natural and artificial cultures. 
. 
MYCELIUM. 
Cultures upon agar media develop rapidly from conidia, 
the mycelium usually becoming visible within a day as a 
* Thom, C. Some suggestions from the study of dairy fungi. Jour. 
Myc. 11: 117-124. (1905). 
