686 A MANUAL OF THE PENICILLIA 



recently isolated or received from such scattered original sources as Sweden, 

 Brazil, South Africa, Panama Canal Zone, and England. 



This species is one of, if not in fact, the most abundant of all the asco- 

 sporic Penicillia in nature. Representative strains have been regularly 

 encountered in this Laboratory in soil population studies and have been 

 received from many investigators abroad. It is apparently world-wide in 

 distribution. 



Penicillium wortmanni Klocker is commonly confused with P. vermicu- 

 latuni Dangeard. Thom (1930) regarded the two species as synonymous. 

 He further concluded that his culture No. 11, which had been designated 

 P. lutemn Zukal originally (1910) upon the advice of Wehmer, represented 

 P. wortmanni Klocker. This opinion was shared by Biourge (1923). Derx 

 (1926), studying the same culture, had observed the characteristic clavate 

 ascogones and correctly identified it with Dangeard's P. vermiculatum 

 (1910). 



In his comparative study of ascocarp formation in the Penicillia, Emmons 

 (1935) reported and figured significant differences in the perithecial initials 

 of Penicillium wortmanni and P. verrniculatum, and his observations have 

 been confirmed in our present study. In addition, we have found that 

 cultures of P. wortmanni consistently produce more restricted and slower- 

 growing colonies. Penicilli in the latter species are more regularly biver- 

 ticillate and symmetrical, although in their most typical aspect they are 

 strikingly similar in the two species. The conidia of P. wortmanni are 

 usually slightly larger and more definitely pointed. In neither species can 

 perithecia be said to develop a true wall, but strains of P. vermiculatum 

 generally show a more definite bounding hyphal network than strains of 

 P. wortmanni. Ascospores in the two species are strikingly similar but 

 lend to be smaller and less conspicuously spinulose in P. wortmanni. 



\]n\ike Penicillium vermiculatum Dangeard, P. avellaneum Thom and 

 Turesson, and P. stipitatum Thom, which often lose the capacity to produce 

 perithecia upon continued laboratory cultivation, all of the strains of P. 

 wortmanyii in our possession continue to produce some ascosporic structures. 

 This capacity is substantially reduced in some of our strains that have been 

 in the Collection for ten years or more, but in no case has it disappeared 

 completely. Recent isolates usually develop both abundant perithecia and 

 conidial structures. 



Penicillium helicmn Raper and Fennell, in JNIycologia 40 : 

 515-518, fig. 3. 1948. 



Colonies on Czapek's solution agar growing restrictedly, commonly not 

 exceeding 1.5 to 2.0 cm. in 2 to 3 weeks at room temperature, comparatively 

 thin (fig. 150A), with vegetative mycelium largely submerged and withsur- 



