38 



CULTURAL STUDIES OF SPECIES OF PENICILLIUM. 



Colonies liquefy gelatin, but slowly and incompletely, and give a neutral or acid 

 reaction upon all litmus media. Under different conditions of culture and acidity the 

 discoloration of the medium varies from yellow to orange and deep red. Produces dis- 

 colorations upon commercial timbers. Habitat, pine wood, which is strongly colored 

 by it. 



Culture received from the author, G. G. Hedgcock, of the Forest Pathological Lab- 

 oratory, Bureau of Plant Industry, United States Department of Agriculture. 



Since the publication of his description of this fungus (1906) Hedg- 

 cock 9 has reached the conclusion, concurred in by the writer, that 

 this species can not be regarded as identical with the species described 

 by Corda as P. aureum. He notes that this species is a common agent 

 in the discoloration of pine wood, hence proposes the name P. pino- 

 fliilum (here first published). Careful consideration of Corda's 

 figure and description would establish a strong presumption that 







Fig. 6. — Penicillium pinophilum Hedgcock: a, young conidial fructification showing conidiiferous cells at 

 apex of central branch before all the branches appear (X 1,600); 6, a verticil of four branches, upon one 

 of which fruit appears (X 1,600); c, d, conidiiferous cells and conidia (X 1,600); c, rope of hyphse bearing 

 conidiophores sketched (X 140); /, g, forms of conidial fructification (X 140). 



the form described by him would not now be considered a species of 

 Penicillium. 



CULTURAL DATA. 



Color, conidial areas green, vegetative mycelium colorless or studded with yellow 

 granules; reverse of colony red; color in media, red. 



Odor, none. 



Fifteen per cent gelatin in water, growth slow, surface growth of conidiophores 

 and green conidial fructifications only; liquefaction, none or very slow (in acidified 

 cultures only after several weeks); litmus reaction, acid. Potato agar and bean 

 agar, mycelium studded with yellow granules, conidial areas strict, green; reverse 

 of colony, red. Potato plugs, poor growth, not typical. Cohn's solution, spores 

 germinated only. 



