64 



AGRICULTURAL AND INDUSTRIAL BACTERIOLOGY 



ble Aspergilli. 



Penicillium. Certain species of this genus probably are 

 the most common of all molds. They are variously colored, 

 usually grayish-green or bluish-green. They occur upon 

 the surfaces of decaying vegetable matter such as silage, 

 oranges, lemons, bread, jams, jellies, etc. The spores are 

 relatively common in the air and are usually met with in 

 the laboratory. In many respects these organisms resem- 

 They differ primarily in the manner in 

 which the spores are produced. The erect 

 conidiophores branch at the tip, a group of 

 two, three, or four branches usually being 

 formed. These continue parallel to each 

 other and usually again branch. This may 

 occur a second or a third time. The 

 terminal branches pinch off chains of spores 

 which may reach a considerable length. 

 Microscopically the conidiophore with its 

 branches, tip and long chains of spores re- 

 sembles a brush, hence the name Penicillium 

 (a little brush). 



Certain of the species of Penicillium are 

 of importance in the ripening of cheese^ 

 particularly Roquefort, in which Penicil- 

 lium roquefortii is present, and Camem- 

 bert, in which Penicillium camembertii occurs. The char- 



E. Tip of conidiophore club-shaped, 

 sterigmata both lateral and termi- 

 nal A. psreudoclavatus. 



EE. Tip of conidiophore hemispheri- 

 cal, sterigmata terminal A. nidulans. 



BB. Spores black or dark brown. 



. With unbranched sterigmata A. calyptratus. 



CC. With branched sterigmata A. niger. 



BBB. Spores, yellowish-brown, yellow, brown, 

 or reddish. 



D. With unbranched sterigmata, coffee- 

 brown spores A. wentii. 



DD. With branched sterigmata, yellow- 

 brown spores A. ochraceus. 



FIG. 43. PENI- 

 CILLIUM. 



