MONOVERTICILLATA 



171 



we employ. Attempts at further separation would necessitate recognition 

 of species based, in many cases, upon individual strain differences. 



vi^-^ii 





o 



■c 



B2 



Bl 



/ 



Fig. 48. Penicillium frequentans series. A, P. frequentans Westling: Ai, Habit 

 sketches of penicilli showing characteristic columns of conidia; A^, Typical peni- 

 cillus seen under oil immersion. B, P. purpurrescens (Sopp) n. comb.: Bi, Habit 

 sketch of conidial structures; Bi, Typical penicillus greatly enlarged. C, P. spinu- 

 losum Thom: d and Co, Habit sketches and detailed drawing of penicilli, respectively. 



The separations proposed here may seem somewhat arbitrary to some 

 workers, while to others it may appear that we have grouped together too 

 large numbers of described and previously recognized forms. Suffice it to 

 say, our treatment of the series is based upon careful comparative examina- 



