TYPES OF BASIDIA 279 



Auricularia slender sterigmata arise that bear the basidiospores 

 at the same level. In Phleogena (Pilacre) basidiospores are pro- 

 duced in a row down one side of the epibasidium. In Septo- 

 basidium the probasidium is thick-walled, quite as in the rusts, 

 and the slender septate epibasidium bears its basidiospores on 

 rather long sterigmata. In this type of basidium with its several 

 minor modifications the nuclear spindles are longitudinally 

 oriented, and such basidia are said to be of the stichobasidial type. 

 The Tremellales are characterized by another basidial type. 

 The spherical or elongate basidium becomes divided by a vertical 

 septum after division of the primary diploid nucleus. After di- 

 vision of each of these nuclei another vertical septum at right 

 angles to the first is laid down, so that the basidium, as seen from 

 above, is cruciately divided. Each quadrant then bears a slender 

 sterigma on which a single haploid basidiospore is apically pro- 

 duced. The nuclear spindles among Tremellales are oriented 

 transversely to the longitudinal axis of the basidium, such basidia 

 being therefore regarded as of the chiastobasidial type. 



Among the Heterobasidiomycetes there exists still another 

 type of basidium. Here the primary diploid nucleus divides 

 twice, the spindles being longitudinally placed. Then a tuning- 

 fork-shaped process arises at the apex of the basidium. Two of 

 the nuclei pass into basidiospores, 1 at each tip of the fork, and 

 the other 2 nuclei eventually disintegrate. This type occurs 

 among the Dacryomycetales. 



The basidia of the Hymenomycetes and Gastromycetes repre- 

 sent another type. In general they are slender, clavate to broadly 

 clavate in the Hymenomycetes, and nearly globular in the Gas- 

 tromycetes. The fusion nucleus characteristically undergoes 2 

 divisions to make 4 haploid nuclei. Sometimes there are 1 or 

 more additional divisions. Usually 4 slender sterigmata arise 

 from the basidial apex, and a uninucleate basidiospore is borne on 

 each sterigma. In Tulostoma the sterigmata may be somewhat 

 lateral. In certain gill fungi, such as Ama?iita bisporigera, Cama- 

 TOphylhis virgmeiis, Cantharellus cornucopioides, Mycena metata, 

 and Psalliota campestris [Bauch (1927), Buhr (1932), Smith 

 (1934), and Colson (1935)], and in the coral fungi, Clavaria ci- 

 nerea and C. cristata, 2 basidiospores, instead of 4, are regularly 

 produced on each basidium. Bauch (1927) has shown that such 

 basidiospores are rarely binucleate, although they are known 



