Dodge: Life History of Ascobolus magnificus 123 



Papulospora magnifica 



A very good illustration of the inadequacy of a classification 

 of fungi based on asexual stages is the genus Papulospora as 

 understood by Hotson (3). A true papulospore might be de- 

 fined as one in which one or two large central storage cells are 

 surrounded by a covering of hyphae which develop from blister- 

 like outgrowths of the storage cell. Hotson has described a 

 number of species and points out that these forms may belong to 

 perfect stages of species in various groups of fungi, that is, 

 Papulospora is the bulbil asexual stage liable to be found any- 

 where among the Ascomycetes. 



Papulospores of the type shown in Plate 8, figs. 5, 6, 7, and 

 Text figs. 21, 25, appear in about ten days in all cultures of A. 

 magnificus which I have obtained by germinating ascospores. 

 The spores are very hard to germinate, but I have been able to 

 make hundreds of "pure" cultures, many of them one-spore 

 cultures. The papulospores do not germinate readily, either, so 

 that I have made only a few cultures by growing them. I have 

 transferred the mycelium of these one-papulospore strains to sev- 

 eral kinds of media without being able to obtain the ascocarps 

 of the Ascobolus. At my request Professor J. W. Hoston made 

 an extensive study of the Papulospora and published his results 

 describing the species as P. magnifica (4). He was unable to 

 obtain ascocarps from the culture which I sent him, and there- 

 fore concluded that there was not sufficient evidence to warrant 

 assuming without further proof that it might be an asexual stage 

 of A. magnificus. He thought it might occasionally be an intra- 

 hyphal parasite as I had once imagined (7). Mr. E. S. Schultz 

 also made a pure one-spore culture of this Papulospora for me. I 

 was unable to obtain ascocarps by growing this strain in various 

 media. Papulospora stages have been connected with the Mela- 

 nosporas and there is a very close resemblance between the bul- 

 bils of P. magnifica, P. Candida, P. parasitica, P. coprophila and 

 those of the Melanosporas studied by various investigators. 



