BASIDIOMYCETES 



397 



migrates into the germ tube, while the other remains in the spore. A 

 septum is formed between them and the germ tube grows to a more or 

 less elongate uninucleate mycelium. 



In the third type, which includes Coprinus fimetarius, Pholiota praecox, 

 Hypoloma perplexum and Ar miliaria mucida (Nichols, 1905, Levine, 

 1913; Bensaude, 1918), the mature basidiospores may be uni- or binu- 

 cleate. The two nuclei migrate rapidly into the young germ tube 

 (occasionally branched) and complete a large number of mitoses without 

 laying down septa (Fig. 264, 2). In certain species, e.g., Coprinus 

 fimetarius, one nucleus remains behind in the basidiospore and the further 

 development proceeds from the nucleus which migrates into the germ 

 tube. After a few days, the primary coenocytic mycelium (often with 

 thirty nuclei) becomes septate, and consequently uninucleate (Fig. 264, 

 3). After this happens, these first three types cannot be differentiated. 



Fig. 264. — Coprinus fimetarius. 1. Germ tube with two nuclei. 2. Coenocytic hypha. 

 3. Hyphal cell with oidia. ( X 700; after Bensaude, 1918.) 



In the fourth type, which includes Corticium bombycinum (C. ter- 

 restre) (Kniep, 1913) and most Gasteroinycetes, the mature basidiospores 

 are always binucleate, and, in contrast to the second and third types, the 

 nuclei always appear as a dicaryon, (Fig. 265, 2 to 6). They migrate 

 together into the germ tube and thereafter divide conjugately; therefore 

 we must regard this last type as secondary mycelium and conclude that 

 the uninucleate, haploid, primary mycelium found in the first three 

 types is lacking. 



From the standpoint of change of nuclear phase, the haploid mycelium 

 corresponds to the usual vegetative mycelium of the Ascomycetes, and 

 is propogated (as in the latter) by all sorts of secondary spore forms, as 

 conidia, oidia and gemmae. The "conidia" (spermatia) show types 

 of organization similar to those of the Ascomycetes and for the most 

 part may not be distinguished from them. In some parasitic families 

 (Uredinales), as in the Sphaeriales of the Ascomycetes, they are cut off 



