Chapter XVII 

 ASPERGILLUS NIGER GROUP 



Outstanding Characters 



Conidial bonds carbon black, brownish-black or purple-brown; in mutants, 



shading toward colorless but not actually white. 

 Heads typically large and globose; but small heads produced in some 



strains, in extreme cases consisting of only a few sterigmata and chains 



of eonidia. 

 Conidiophores smooth, colorless or tinged with yellow --brown colors in 



the upper one-third or less, splitting lengthwise into strips and shreds 



when broken. 

 Vesicles globose in large heads, fertile over the entire surface; in small 



heads often reduced to dome-like apices of short conidophores ("fumi- 



gatifonn")- 

 Conidia rough, mostly showing bars or bands of brown-black coloring 



matter. 

 Sclerotia characteristic of many strains, more or less irregular, ranging 



from buff through gray to almost black. 



The designation "Aspergillus niger" 1 is commonly used to cover a great 

 aggregate of Aspergilli differing in details of morphology, but having in 

 common the production of conidial heads which are black, brownish-black, 

 purplish-brown, or in some strains lighter in color but retaining the general 

 appearance oi the group. 



When examined by the hundred as they are isolated from natural sources, 

 the vast majority of cultures studied show the general morphology of 

 Aspergillus niger van Tieghem. if a reasonable allowance be made for strain 

 variation which is characteristic of all of these groups of cosmopolitan molds. 

 At the same time, other organisms scarcely distinguishable in general 

 cultural appearance often show marked differences in microscopic char- 

 acters, hence have formed the basis of species descriptions. Other species 

 have been segregated by various authors in the belief that they bore an 

 obligate relation to the particular substrata from which isolated (e.g.. 

 .4. strychni. A. ficuum), but such specificity has not proved dependable. 

 There are. in addition, a considerable number of probable variants whose 



1 Biourge in his last manuscript proposed the use of the name Pulli for the black 

 Aspergilli in recognition of the belief that Mieheli J~29^ had one of them before him 

 as his "Aspergillus capitolus capitulo pullo." 



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