THE GENUS PENICILLIUM . 381 



The fungus grows best about 25 to 27 C. 



(ii) P. camemberti, Thorn. A form or species of 

 Penicilttum, associated with the ripening of Camembert 

 cheese, appears to be closely related to P. glaucum, but 

 differs from it in some of its features. It is probably 

 the same as P. album of Epstein, and P. candidum 

 described by Rogers as occurring on Brie cheese. 



At first its hyphae are very white ; in the early conidial 

 stages it has a greyish-green tinge, becoming greyish- 

 white later. 



The sterigmata, 2 to 4 usually together, are 8 to 1 1 //, 

 long, 2 to 3 ,<A broad ; the conidia in a young state are 

 sometimes slightly elliptical, but ultimately round and 

 smooth, from 4.5 to 5.5 ^ in diameter and yellowish- 

 green when ripe. 



The casein of milk is peptonized by it without 

 coagulation. 



(iii) P. brevicaule, Sacc., differs somewhat from the 

 ordinary types of Penicillium in having its spores some- 

 times placed directly on the mycelial hyphae instead of 

 on special sterigmata. At first the fungus is white, but 

 later turns brownish-yellow or brown ; we have seen a 

 deep orange form on the " coats " of Stilton cheese. 



The sterigmata are comparatively few, usually bearing 

 single terminal round conidia, which, when ripe, are 

 5 to 7 [L in diameter, with warted surfaces. 



Weigmann and Wolff found a form of this fungus in 

 the dung of cows fed largely on turnips (see p. 355). 



Ex. 165. Place a piece of mouldy Stilton cheese, or mouldy 

 bread, on some damp blotting-paper in a deep Petri dish. Leave 

 for a day or two until active growth of the mould commences. 



(a) Remove a portion of the blue mould with a pair of 



