158 Transactions British Mycological Society. 



only 1-3 ju. in length when simple, and are usually hyaline at 

 the tip. Some are slender and others are comparatively stout 

 arid clavate in shape. They arise from any part of a hyphal cell 

 or in groups of two or more from cells resembling basidia. No 

 spores have been found in association with them, and their 

 function is therefore obscure, but their arrangement points to 

 the possibility of their being abnormal sterigmata. The supposed 

 sterigmata are short and simple and are borne in twos and fours 

 on rounded hyaline basidia which are themselves cut off from 

 hyphae resembling the vegetative hyphae of the Rhizoctonia 

 (Plate V, fig. 9), but there is no extensive development of the 

 latter hyphae to form a special hymenophore. No spores have 

 been seen on the sterigmata. 



The supposed hymenophore was found on the surface of the 

 wood of a Grevillea root which was still internally moist, and 

 from which no bark had been detached until the material was 

 examined in the laboratory. It is apparently of an imperfect 

 nature, induced, it may be, by a gradual process of abortion, 

 and its present significance in the life-history of an organism 

 which is well-equipped with vegetative means of reproduction 

 and spread may well be of little and diminishing importance. 

 As far as is known, the hymenophore occurs only between the 

 bark and wood of a root which is far from the stage of decay 

 that would liberate the basidiospores of the fungus. 



The Grevillea Rhizoctonia in Pure Culture. 



Cultures of the Rhizoctonia have been obtained from root 

 fragments containing hyphae and from pieces of sclerotial plates 

 and scrapings of the supposed hymenophore tissue, in dealing 

 with which every care has been taken to guard against the 

 presence of contaminating elements. The inocula have been 

 thoroughly sterilised by dipping in alcohol and by subsequent 

 flaming or immersion in a saturated solution of corrosive sub- 

 limate in alcohol. In many cases, both treatments have been 

 given to the inocula, and, in consequence, a large proportion 

 of them has been rendered incapable of growth. Despite many 

 attempts, neither rested nor fresh sclerotia have been induced 

 to germinate in culture media or in soil or sand. The fungus 

 grows well on agar media (prune + 15°, oatmeal + 10°) and on 

 sterilised filter paper moistened with sugar-cane decoction. The 

 growth of the fungus renders the solid media dark in colour 

 after a few days and black when the development of sclerotia 

 is well-advanced. In most cases, young hyphae are visible in 

 from 12-24 hours, and in all cases sclerotial formation follows 

 almost at once. The young hyphae are colourless, branched, 

 sparingly septate at first, and swollen at the tips; they appear 



