PEXICILLIUM ROQUEFORTI. 



35 



desiring a culture of this species can always obtain it by purchasing 

 cheese of this type. It also occurs frequently in ensilage and is 

 often found as a contamination in laboratory cultures of other fungi. 

 The species is well marked by cultural characters from which it can he 

 readily recognized when once studied. Its agency in the ripening 

 of Roquefort, Gorgonzola, and Stilton cheeses is discussed in another 

 paper (Thorn 85 ). 



CULTURAL DATA. 



Color, gray-green to clear green, becoming brownish when old if exposed; reverse 

 colorless or cream; color in media, none, or in some cases a Blight and evanescent 

 greenish 1 ingi 



I >dor, none | unless accountable for some odor in Roquefort cheese). 



WW lillW 



j 



Fig. i. Penicillium rnt/nttnrti Thorn: a, jciri of conidiophore and of base of fructification, highly mag- 

 Ing production of basidia on sides as well as a< apex of basidiophore; 6, c, other types of 

 branching; •/. young conidiophore jus! branching; <, /. basidia and the formation of conidia, highly 

 magnified; <j, U,j. diagrams of types of fructification as seen under low power i < 80); /.-. /, m, u, germina- 

 tion of conidia ana new conidia produced directly on the first hyphse. I From Bulletin 82, Bureau of 

 Animal Industry.) 



Fifteen per cenl gelatin in water, good growth, n<>t heavy; liquefaction, none, or 

 partial after '1 to :'. weeke in acidified cult ures; lii mus reaction, alkaline. Potato agar 

 ami bean agar, gray-green, loose, becoming dense and deep green when sugar is added. 

 Potato plugs, characteristic. Raulin's fluid, \ ery dense, deep green colonies. Cohn'e 

 solution, Blighl growth. 



Synthetic fluid i Dox's), carbon supplied a-: Cane sugar, Blow growing bul typical 

 colonies up to -'in per cent, persistently lti^h, not acid. Lactose '■'< per cent, weak 



" Weidemann ' records the production of a red color in cane-sugar solution by this 

 species. The writer has nol obtained this color in his culture 



