HISTORICAL 7 



thecia as described and illustrated, both in form and development, approx- 

 imate those seen in strains now assigned to species in the Carpenieles and 

 P. javanicum series (fig. 2). Other of his penicilli might belong to some 

 species such as P. egyptiacum van Bejrnia, or possibly P. asperum (Shear), 

 in which case they might easily have developed upon the same mold that 

 produced the sclerotioid perithecia with tardy ascospore formation. His 

 ascospores, with equatorial ridges and rough side walls, could have be- 

 longed to some species such as P. asperum or P. baarnense van Beyma. 

 No one can be certain ^^•hether Brefeld worked with a mixture of two 

 species; or whether he worked with a single Penicillium, and some of his 

 drawings (obviously schematic) are misleading; or whether he worked with 

 a single strain and illustrated it accurately throughout. We can say, 

 however, that no single species is known to us which combines all of the 

 characteristics illustrated by Brefeld. Wlien one considers the level of 

 laboratory culture techniques of his day, and the state of mycological 

 knowledge then existing, one cannot but admire the skill and care ex- 

 hibited in his w"ork. 



The use of the name Penicillium glaucum for the apple-rot organism was 

 continued in Sopp's Monograph (1912, p. 48) and in Wehmer's Beitrage 

 (1893). Both men were students in Brefeld's laboratory, hence the con- 

 tinuity of this usage is evidence of an understanding among them that this 

 organism should be regarded as P. glaucum. 



Wehmer, in 1895, published his studies of the Penicillia occurring upon 

 rotting fruit. He figured and described the destructive effects of Peni- 

 cillium expansum on apples, pears, and grapes — but under the name 

 P. glaucum. The olive colored rot of oranges, already described by 

 Saccardo as P. digiiatum in 1880 and distributed in Mycotheca Italici, 

 was called P. olivaceum, and the soft rot organism with blue-green colors 

 was correctly regarded as new and named P. italicum. In the same year 

 he published his study of citric acid-forming molds, to which he gave the 

 name Citromyces, and his study of ascospore formation in P. luteum Zukal. 

 Wehmer was the first investigator to pay particular attention to the phys- 

 iological and biochemical activities of molds, and he prepared the studies 

 of this group in the second edition of Lafar's Technische Mj^kologie (1906). 



Sopp^ records that he recognized as early as 1890 that the name Peni- 

 cillium glaucum, in addition to designating the apple rot organism, was 

 being used to cover more than a single species. Elfving came to the same 

 conclusion in 1895. In 1898, Sopp separated certain of the forms found 

 active in cheese ripening as P. aromaticum. Unfortunately his descrip- 

 tions of these organisms were entirely inadequate, apparently depending 

 for identification primarily upon their presence upon particular varieties 



1 Early papers signed Olav Johan-Olsen. 



