704 



ADDITIONAL EXERCISES 



PeniciUinm cxpansum (Fig. 243) which can always be obtained from apples decaying 

 in storage. Colonies of this mould upon gelatin and potato, or bean agar, are green, 

 becoming gray-green and later brown. The conidiophores are tufted into corem- 

 ium-like clusters. 



The conidia fructifications consist of one to three main branches bearing verticils 

 of branchlets supporting crowded whorls of sterigmata. Conidiospores are elliptic 

 2 by 3.3A1, green, persisting in chains, when mounted. 



'*oi;f/'/II 



MM ;,/ 



Fig. 243. — Penicillium expansum. a, b, f. Arrangement of branches of conidial 

 fructification; c, d, e, conidiiferous cells and chains of conidiospores; g, h, j, k, I. 

 sketches of fructification; m, n, o, germination of conidiospores; r, s, sketches show- 

 ing in ^ loose aggregations of conidiophores, r coremmm. (After Thorn.) 



Penicillium Roqiieforli (Fig. 244) is the agent in the ripening of Roquefort, 

 Gorgonzola and Stilton cheeses. Colonies on potato agar quickly become green, 

 becoming a dirty brown when old. The velvety mycehum consists of radiating 

 branching hyphae giving an indefinite margin. The conidiophores arise separately 

 and in acropetal succession from the growing parts of submerged hyphas, 200 to 300M 



