112 A MANUAL OF THE ASPERGILLI 



(3-percent sucrose) colonies restricted, raised in center, thinning toward 

 margin, consisting of abundant conidial heads and interlacing hyphae, buff 

 to clay colored; reverse yellow to tawny. Conidial heads abundant, dull 

 green, up to 200m in diameter and commonly splitting into fairly well-de- 

 fined columns, conidiophores up to 1,000m in length. Conidia subglobose 

 mostly 5.5 to 6.0m but occasionally up to 7.0m in long axis, spinulose. 



ASPERGILLUS RUBER SERIES 



Ascospores lenticular, 5.0 to 6.0m by 4.0 by 4.8m, colorless, with broad, 

 shallow furrow generally evident and flanked by low ridges, and with walls 

 smooth except for minute roughness along the equatorial ridges. 



This series includes a great number of strains showing variations in cul- 

 tural appearance but producing ascospores of a limited size range and 

 fairly well-defined pattern. For this particular study some 30 strains, 

 received from various culture collections and contributors and selected 

 from the isolations made in this laboratory over a period of many years, 

 have been chosen for repeated culture and examination. Among these, 

 many strains appear distinct, but their differences are commonly bridged by 

 intermediate forms. Separation within the series, therefore, must be along 

 one of the following lines — either (1) strains must be separated upon minor 

 characters, such as differences in the intensity of pigmentation, slight 

 variations in ascospore character, etc.; or (2) strains must be set off in 

 broad and elastic subgroups, in some cases including large numbers which 

 vary appreciably in detail. The second alternative is desirable, for the 

 first can lead only to increased hairspliting and end in greater confusion 

 than that which already exists. 



Spieckermann and Bremer's designation Aspergillus ruber (1902) is as- 

 signed to the series, because its members are predominantly producers of 

 an intense red pigment and bear ascospores of the general size and pattern 

 described by these authors. The only other described fungus possessing a 

 similar ascospore and characterized by its red color is Bainier and Sartory's 

 Aspergillus sejunctus (1911b). 



Although it is now quite impossible to say what particular fungus either 

 pair of investigators had at hand, both are believed to have worked with 

 members of the large series now under consideration. Aspergillus ruber 

 is retained since its description is more adequate for the series in addition 

 to being the prior species. 



To accentuate cultural similarities and differences between the strains 

 studied, a wide variety of culture metiia has been employed. Based upon 

 their appearance in culture, the strains fall into a few well-defined sub- 

 groups (see figs. 29 and 30). The strains belonging to one of these seem 



