MONOVERTICILLATA 223 



approximate Sopp's Citromyces fuscus, although liis species is known only 

 from the original description since t3'pes were never distributed to other 

 investigators. Consistent with Sopp's description, conidial areas are 

 fuscous in age, conidiophores fairly long and characterized by limited 

 vesicular enlargement, sterigmata are borne in a compact cluster sugges- 

 tive of a simple Aspergillus, and conidia are large, gloljose, echinulate and 

 brown. In our culture, conidiophore walls show a light yellow-brown 

 color of the approximate shades seen in the Aspergillus ustus group. \A'Tiile 

 clear evidence supporting such a view is not at hand, the possibility that 

 P. fuscum may represent another species transitional in the direction of 

 Aspergillus should not be overlooked. 



Members of the series are typical soil organisms, and strains duplicating 

 or approximating those cited in the text below have been isolated re- 

 peatedly in our laboratory over a period of many years. Such cultures 

 commonly lose their capacity to produce abundant conidia and, being 

 somewhat difficult to maintain in artificial culture, are often soon lost 

 from collections. If long maintained, they commonly develop as practi- 

 cally nonsporulating, floccose growths hardly suggesting the original iso- 

 lates except for the scattered production of conspicuously roughened 

 globose spores. 



Penicillium restrictum Oilman and Abbott, in Iowa State College Jour. Sci. 



1: 297, fig. 32. 1927. See also Thom, The Penicilha, pp. 



176-177, fig. 20. 1930. 



Colonies on Czapek's solution agar growing rather restrictedly, attain- 

 ing a diameter of 2.0 to 2.5 cm. in 12 to 14 days at room temperature, 

 azonate, appearing floccose, 1 mm. or more in thickness, consisting of a 

 tough basal felt bearing a loose aerial mycelium of delicate hyphae, about 

 1.5 to 2.0m in diameter, somewhat radially wrinkled in most strains, white 

 or nearly so, bearing few conidial structures mostly after 1 week to 10 days 

 (fig. 61 A), conidia at first pale blue-green, shading quickly to dull gray 

 (Ridgway, PI. LII); exudate limited in amount, clear to pale yeUow; odor 

 none; reverse in j^ellow to peach or clay colors (R., PI. XXIX); aerial 

 hyphae developing numerous, short spur-like branches, some of which 

 remain sterile, others of which bear conidia as isolated sterigmata, but 

 which typically develop into conidiophores, mostly 25m or less in length by 

 1.2 to 1.8/i in diameter, smooth-walled; penicilli consistently small, mostly 

 monoverticillate or occasionally irregularl}' branched and sometimes show- 

 ing one or two secondarj' penicilli on the same conidiophore; sterigmata 

 often divergent, usually in small clusters up to 6 or 8 in number (fig. 61 C), 

 about o.O/i by 1.5^, narrowed at both ends with conidium-bearing tips 



