48 



CULTURAL STUDIES OF SPECIES OF PENICILLIUM. 



CULTURAL DATA. 



Same as P. brevicaule Sacc, except the following difference noted: 



Conidia cream, somewhat larger than P. brevicaule. 



Cohn's solution failed to produce characteristic colonies. 



In Dox's solution, with butterfat as a source of carbon, it differs from P. brevicaule by- 

 failing to cause drops of yellow oil to separate out. 



Agar-agar: In repeated cultures this organism has failed to grow well in agar media. 

 In some such cases the spores transferred from the agar to gelatin grew at once. Some 

 cultures upon agar grow slowly and in typical manner, but the development upon all 

 agar media has seemed uncertain. In synthetic solution cultures were obtained when 

 the inoculation of tubes of the same solution with 1.5 per cent of agar added to make a 

 solid substratum produced no growth. 



PENICILLIUM BREVICAULE Saccardo, var. GLABRUM Thorn, n. var. 



Colonies white or only slightly yellowish-tinged in all gelatin media, grow not at all 

 or with difficulty on agar of most formulae. Aerial portion consisting of short, closely 

 crowded conidiophores making a powdery surface overgrown by loosely trailing 

 hyphte and ropes of hyphse, spreading broadly over the substratum. Conidiophores, 

 short, mostly 10-30^, arising directly from submerged hyphse or numerously and irregu- 



Fig. 14.— Penicillium brevicaule, var. glabrum: a, b, c, branching of conidial fructification (X 900); d, chain 

 of conidia (X 1,400); /, formation of conidium on young branch (X 1,400); g, h, sketch of appearance 

 in culture (X 140); m, n, o, germination of conidia. 



larly borne as perpendicular branches of the superficial hyphse and ropes of hyphse. 

 Conidial fructifications from simple chains of spores to fairly complex penicillate 

 groups of branchlets resembling P. brevicaule, but mostly less complex. Conidia 

 obovate, pyriform 7-8 by 8-10/t or almost globose, 7-9//, smooth, white, rather thick- 

 walled and retaining their power to germinate for many months. In old potato and 

 other cultures black sclerotia are formed in the substratum but do not produce asci. 

 Liquefies gelatin rapidly (within one week), gives a strong alkaline reaction and 

 ammoniacal odor. 



Habitat, found repeatedly on imported Camembert cheese and secondarily upon 

 domestic soft cheese, where it grows into prominent cottony patches indistinguishable 

 to the eye from the white variety of P. brevicaule. This fungus is separated from 

 P. brevicaule by its smooth white spores and the production of the black sclerotia in 

 the substratum. 



