CHROMOGENIC FUNGI WHICH DISCOLOR WOOD. 105 



and that of Thorn * 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 



* Thorn, C. Some suggestions from the study of dairy fungi. Jour. 

 Myc. 11 : 117-124. (1905). 



