GENERIC DIAGNOSIS AND SYNONYMY 15 



than actual homologies, members of several different genera have, from 

 time to time, been given specific names as Penicillia. 



Link included three species, namely: PeniciUium glaucum, P. candidum, 

 and P. cxpansum. Thom, in conference with Shear (Thom, 1910), con- 

 cluded that P. expansum could be accepted as the type species for the 

 genus since it was represented by known material in the form of the apple 

 rot PeniciUium} 



With cultures of PeniciUium expansum thus representing the nearest 

 verifiable approach to Link's material, Thom (1910, 1930) felt justified in 

 emending Link's generic description to include a fairly homogeneous group 

 of series and species, and equally to exclude other types, or aggregates. 

 In doing so it became essential to recognize that in certain series asci 

 were produced by species or strains morphologically indistinguishable in 

 their conidial forms from strains which failed to produce asci. Following 

 the position earlier taken by Thom, the authors of this Manual believe that 

 the whole complex aggregate can best be covered by an emended generic 

 description of PeniciUium. 



We are fully aware that different workers since Link's time have as- 

 signed to PeniciUium species showing conidial fructifications that present 

 or suggest a penicillate arrangement without attempting to analyze the 

 morphology of the conidial apparatus, or to give any reason other than the 

 suggestion of a brush or broom (the penicillus). We wish to emphasize 

 also that Brefeld called his ascosporic form PeniciUium, and did not fabri- 

 cate a new generic name because a mold that he believed to be a known 

 PeniciUium produced ascospores. With a century and a quarter of Peni- 

 ciUium literature before us, we see no alternative but to use the name 

 PeniciUium for both ascosporic and conidial forms unless and until it is 

 shown that seriously discordant elements would be included. Gliocla- 

 din7n, Scopidariopsis, Paecilomyces, Byssochlamys, and perhaps some 

 other forms \\hich have at times been assigned to PeniciUium, are readily 

 excluded by their conidial fructifications or ascosporic apparatus. Our 

 emendation of the generic diagnosis follows: 



PeniciUium Link, in ''Observationes," p. 17. 1809; emended, Thom, in 



the U. S. Dept. Agr., Bur. Anim. Ind., Bui. 118, pp. 27-28. 1910; 



also Thom, The Penicillia, pp. 8-9. 1930. 



Vegetative mycelium abundant, entirely submerged or more or less 

 effused, monopodially branching, septate, commonly showing vegetative 

 anastomoses, colorless or secondarily colored by products of metabolism 



' The bases for accepting PeniciUium expansum Link as the type species for the 

 genus were discussed in greater detail by Thom in 1910 and 1930. 



