ORDER AURICULARIALES 439 



inella, parasitizing upon scale insects; Hei-pohasidium filicinum (Rostr.) 

 Lind and Platycarpa upon ferns; etc. According to Boedijn and Steinmann 

 (1931) the East Indian species of Helicohasidium are parasitic upon roots, 

 while H. purpureum (Tul.) Pat. is parasitic on various plant roots and 

 crowns in Europe. 



Clamp connections have been recognized in Auricularia, Phleogena, 

 Helicohasidium, Jola, Helicogloea, etc. H. L. Barnett (1937) reported that 

 the mycelium of Auricularia derived from single spores, and therefore 

 monocaryotic, lacks clamp connections but that when two such mycelia 

 of opposite sexual phase come into contact the resulting dicaryotic myce- 

 lium may be recognized immediately by the presence of these structures. 



The spore fruits are external and vary from a more or less felt-like 

 film to a thin crust or to firm shelf-like structures standing out from the 

 substrata. In Phleogena they are upright and stipitate with an enlarged 

 head. In size they vary from a few millimeters to several centimeters. 

 Septobasidium forms a more or less felted layer over the twigs and larger 

 branches of the host with various tunnels and chambers in which the scale 

 insects are protected or through which the larvae may travel. The basidia 

 are formed on the outer surface of the felted mycelium. In some genera 

 the spore fruits are gelatinous when wet, drying down to a horny crust or 

 cushion. Other genera on the contrary, such as Phleogena and Septo- 

 basidium, do not become gelatinized with moisture. 



In the gelatinous types of spore fruits, e.g., Auricularia, the basidia 

 may be situated below the surface or at least with only the upper end 

 reaching the air. This necessitates the formation of tube-like extensions 

 from the four cells of the basidium to the surface where each develops a 

 sterigma and bears a spore. This is very similar to the structure of the 

 germinating teliospore of Coleosporium. Where the structure is not highly 

 gelatinized the basidia are superficial and the sterigmata are very short, 

 without any elongated supporting tubes, e.g., Phleogena. 



The basidia are usually the terminal cells of the hyphae but in some 

 species of Helicogloea {Saccoblastia) the basidial primordia may be inter- 

 calary according to Miss Baker (1936). 



No distinction of hypobasidium and epibasidium is apparent in Au- 

 ricidaria, Phleogena, and Herpobasidium. Within the basidial primordium 

 the two nuclei unite and then undergo "the two meiotic divisions, the 

 spindles of the dividing nuclei being parallel to the long axis of the enlarg- 

 ing cell, thus producing a stichobasidial structure. In Helicogloea {Sacco- 

 blastia) the primordial cell of the basidium produces a lateral sack-like 

 "hypobasidium" in which the union of the nuclei occurs. Then sometimes 

 at one end of this sack, but more often from the apex of the primordium 

 the "epibasidium" grows, and in it the meiotic divisions occur. Since this 

 genus includes species with greater or less gelatinization of the vegetative 



