42 



A MANUAL OF THE PENICILLIA 



THE PENICILLUS 



The penicillus (German: "pinsel") is understood to cover the whole 

 branching system (fig. 7) and is measured from the lowest branch upon the 

 main axis to the tips of the sterigmata, or conidium bearing cells. Conidial 



Conidia- - 



Sterigmata 



Metulae= - = 



Branches== - 



Conidiophore 



Fig. 7. The Penicillus. A, Typical monoverticillate penicillus, as seen in Perii- 

 cillium Jreqxientans Westling, consisting of a terminal verticil of sterigmata only. 

 B, Typical asymmetric penicillus as seen in P. expansum Link, showing metulae and 

 branches below the sterigmata. Camera lucida drawings, X 1600. 



chains are excluded. For diagnostic purposes, the average dimension and 

 the range of variation in the branching system must be determined, rather 

 than the measurement and description of a few selected penicilli. The type 

 of penicillus most common to the species can best be determined by study- 

 ing preparations which make possible the rapid comparison of large num- 



