66 



CULTURAL STUDIES OF SPECIES OF PENICILLIUM. 



rapidly, give an alkaline reaction to litmus, digest milk, and color potato agar con- 

 taining high percentage of sugar a deep black. 



Found upon Camembert cheese imported from France. Closely related morpho- 

 logically to P. citrinum, from which it is separated by the longer conidiophores and 

 larger spores as well as the black discoloration of sugar media. 



CULTURAL DATA. 



Color deep (blue) green to brown when old; reverse uncolored, or brown in some 

 media; color in media, none, or brownish to almost black. 



Odor, none. 



Fifteen per cent gelatin in water, deep green, brown when old, rich growth; lique- 

 faction, 7 days, varies from 6 to 12 days in other gelatin media; litmus reaction, alka- 

 line. Potato agar and bean agar, typical, no color below. Potato plugs, dark green, 

 potato blackened. Raulin's fluid, rather weak growth. Cohn's solution, germinated 

 only. 



Efc 



% llgJr 



ill* 



a ill 



771. 



Fig. 24. — Penicillium atramentosum: a, b, c, d, branching of conidial fructification showing unequal 

 length of branches, swollen ends (X 900); e, /, conidiiferous cell and chain of conidia(X 900); g, h, j, 

 sketches of conidial fructifications (X HO); i, coriidia (X 1,600); m, n, o, r, germination of conidia 

 (X 900). 



Synthetic fluid (Dox's), carbon supplied as: Cane sugar, good growth up to 50 per 

 cent, with acid reaction in 50 per cent solution. Lactose 3 per cent, small and slow 

 growth. Lactic acid 0.9 per cent, no growth. Levulose 3 per cent, slowly typical. 

 Galactose 3 per cent, typical, with alkaline reaction. Glycerin 3 per cent, germina- 

 tion. Potato starch 3 per cent, good growth, no color in fluid or reverse of colony. 

 Butterfat, typical, green colonies with reverse brown, and fluid uncolored. 



Milk, curdling (0.25 per cent calcium chlorid added) in 9 days; digestion, rapid, 

 fairly complete; color, brownish to almost black. 



At 37° C, no growth, grew when cooled; check at 20° C, typical. 



PENICILLIUM No. 24. 



(Related to P. atramentosum'!) 



Colonies upon gelatin and potato or bean agar blue-green, becoming brown rapidly 

 when old, or smoky with very dense velvety surface consisting of conidiophores aris- 

 ing in the substratum or just above its surface, with a very abrupt narrow white 



