Chapter I 

 HISTORICAL 



Species of Penidllium are so abundant and so conspicuous in all sorts of 

 stale or decaying organic matter that they constitute a part of the common 

 conception of mold, and are loosely referred to as "blue" or "green" mold. 

 It is easy to guess, therefore, with Brefeld that some Penidllium furnished 

 the material for Aspergillus albus in figure 3, table 91, of Micheli's "Nova 

 Plantarum Genera" in 1729. Again, it is common mycological tradition 

 that Mucor crustaceus of Linnaeus represented some Penidllium,. This 

 name passed from author to author thereafter without added information 

 from real study of specimens. Persoon (1797, 1801) appears to have in- 

 cluded the species in his conglomerate genus Monilia, again with very 

 little evidence of study under higher magnifications. Some think that 

 Linnaeus' species reappears in Penidllium crustaceum Fries (1829), but 

 there is no continuity in materials and no evidence of real study. Sac- 

 cardo, in the Sylloge in 1886 (Vol. IV, p. 78), went so far as to cite Monilia 

 digiiata Persoon as the basis of P. digilatum, although he furnished little 

 proof of the continuity of this view even as tradition. Bulliard (1809) 

 used the name Mucor 'penicillatus for these "broom" or brush-like forms 

 and provided the first reasonably adequate illustration of a mold unques- 

 tionably representing a Penidllium (fig. 1). 



The name Penidllium applied to a genus of fungi first appears in Link's 

 "Observationes" (1809), in which he described very briefly the genus and 

 three species: Penidllium glaucum, P. candidum, and P. expansum. Close 

 scrutiny of these descriptions and all accessory information gives no clue 

 to the identity of the molds which Link actually had under his microscope 

 as P. glaucum and P. candidum, except that they presented the general 

 appearance of the familiar penicillus or brush seen in the microscopic 

 examination of Penicillia. Penidllium expansum was designated as the 

 fruit rot which, in Berlin at that season, clearly pointed to the Penidllium 

 rot of apples and related fruits (see Thom, 1930). We can, therefore, be 

 reasonably certain of P. expansum Link as a recognizable generic type, 

 world-wide in distribution. It is regrettable that Link, in 1824, abandoned 

 his species P. expansum and called all the green Penicillia, P. glaucum. 

 This practice has been followed by many workers to the present day with 

 the result that use of the name P. glaucum now gives httle clue to the 

 real identity of a Penidllium. 



Link's contemporaries, such as Persoon, Fries, and Greville (1823 to 

 1828), accepted Link's genus Penidllium, although their publications 



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