BIVERTICILLATA-SYMMETRICA 579 



tional (more abundant on hay, cornmeal, and 20 percent-sucrose-Czapek 

 agars); exudate lacking or limited; odor pronounced, suggesting mush- 

 rooms; reverse in yellow to orange-brown shades with pigment diffusing 

 throughout the surrounding agar; penicilli varying in form and complexity 

 from comparatively simple (fig. MSA) through irregular patterns to oc- 

 casionall}^ almost biverticillately-symmetrical, borne on very short conidio- 

 phores arising mostly from the substratum; metulae, when present, variable 

 but commonly about lOfx by 2.5/x; sterigmatic cells tapered in the manner 

 characteristic of the group, variable, from 10 to 12ju by 2.0 to 2.ofi; conidia 

 elliptical to ovate or pyriform, variable in size, mostly 3 to 4)u in long axis 

 by 2.0 to 2.5/i, occasionally up to 6 or 7/i by 3.0 to 4.0m, smooth-walled; 

 perithecia round or nearly so, variable in size up to 300/i in diameter with. 

 fairly definite wall composed of compacted hyphae a few cell layers in 

 thickness, usually surrounded by a loose mantle of thick, encrusted, un- 

 coiled and little branched hyphae (fig. 147C); asci produced abundantly 

 throughout the perithecium upon an interlacing network of fertile hyphae, 

 in short chains, subspherical to elongate when mature, about G.5 to 7.5^ 

 in long axis, 8-spored; ascospores as originally described (fig. 147D). 



Colonies on malt agar spreading broadly, up to 7.0 to 8.0 cm. in 2 weeks, 

 plane (fig. 147B), with vegetative mycelium largely submerged, producing 

 abundant perithecia in a dense layer at the agar surface, often overgrown 

 and partially obscured by a loose, ephemeral network of aerial hyphae, 

 azonate, yellow in color near amber to citron yellow (Ridgway, PI. XVI); 

 perithecia as described above; penicilli lacking or sparingly produced. 



Colonies on cornmeal agar spreading broadly, 7 to 8 cm. in 10 to 12 days, 

 very thin, with vegetative mycelium largely submerged, producing scattered 

 perithecia and conidial structures throughout the entire colony; perithecia 

 as above but seldom more than 200/i in diameter; penicilli as described 

 above. 



Perithecial initials (fig. 144A) easily observed in young colonies upon 

 malt and cornmeal agars. Concerning these structures and the develop- 

 ment of perithecia, Emmons reported as follows in 1935 (p. 139) : 



"In Penicilliuin stipiiatum two similar or barely differentiated hyphae arise as 

 side branches, usually from different hyphae, and coil around each other (fig. 7A). 

 After about two turns they fuse by a large pore so that the opening is of a diameter 

 equal to that of the inside of the hypha. This opening is permanent. The two 

 branches that initiate this development are without doubt the ascogonium and the 

 antheridium. From our knowledge of what takes place in other fungi we may assume 

 that fertilization takes place at this point. Cytological proof in this case has not 

 yet been obtained. We would now expect the development of an ascocarp around 

 this structure as in other Penicillia. The actual development is quite different. 

 One of the branches, or the hypha arising from the union of the copulating branches, 

 elongates until it reaches a length of 100-150^ (fig. 7A). It becomes once or twice 



