HISTORICAL 9 



1897. After Dierckx published his "Essai," Biourge took up the task in 

 earnest. He gave a brief survey of this work in a conference at Louvain 

 in 1916, which was pubUshed as a pamphlet in 1920, followed by his IMono- 

 graph in 1923. In this latter work, Biourge followed along the culture 

 lines already proposed by Dierckx, broadened his work to cover most of 

 the studies made by Thorn, and gave a brief Latin diagnosis for some 125 

 species, followed by culture notes in French. The descriptions were sup- 

 plemented by line drawings of the conidiophore, penicillus, and conidia, 

 and colored plates showing the colors and color changes of his colonies. 

 It represented, beyond question, the most comprehensive and elaborate 

 study of the genus made up to that time. 



Unfortunately Biourge 's microscopic work was largely done from fruit- 

 ing structures removed from cultures preserved in alcohol. Furthermore, 

 he paid little attention to the colony habit with its large contribution to 

 our knowledge of the organism as it grows in the culture tube or petri dish. 

 In the main, Biourge had a fairly good idea of the group relationships 

 within the genus Penicillium, and certain of his divisions are tangible 

 enough entities. His Radiata, covering what we now recognize as the 

 Penicillium chrysogenum series, is illustrative. 



Biourge 's conception of the genus in the broadest sense called for the 

 inclusion not only of Coremium, Citromyces, and of more or less related 

 series like Scopulariopsis, Gliodadium, and Paecilomyces, but part or all 

 of several other genera in which figures or descriptions offer suggestions of 

 a penicillate conidial apparatus. 



Zaleski (1927) described as new thirty-five species and one variety of 

 Penicillium from the forest soils of Poland. His descriptions go into 

 unnecessary detail regarding the buckling and wrinkling of colonies upon 

 gelatin, as the substratum becomes liquefied. Methods of microscopic 

 observation followed Biourge to the destruction of much useful information 

 regarding the structure and appearance of the conidium-producing organs 

 as they are developed in the colony. His cultures and notes were sent to 

 Biourge whose comments are given for certain species, but whose opin- 

 ions were not always followed. In the main, however, he accepted the 

 subgenus, section, subsection, and series divisions as given in Biourge's 

 Monograph and fitted his species into this scheme insofar as possible. He 

 apparently confined his study to the soil organisms which he isolated, 

 hence had no background of comparative knowledge of the many cosmo- 

 politan saprophytes already recognized as belonging to the genus. Care- 

 ful comparative study has tended to reduce most of his species to synon- 

 omy with other species previouly described. 



Thom, in his comprehensive Monograph, brought together all of the 

 material on the taxonomy of Penicillium published up to that time (1930). 



