94 riag Sniut of Wheat. 



immediately after maturity and placed directly in water on a slide, 

 but they did not germinate. With material, however, about a month old, 

 and kept seven days on soil, a small proportion of the spores germinated in 

 water after 24 hours. There was considerable variety, but it consisted gene- 

 rally of a promyceUum l-(3 celled, bearing at its apex 2-6 conidia. The pro- 

 mycelium reached a length of 66 /;< and a breadth of 3-5 \i. The conidia at 

 the apex were usually of unequal length, and they might either be unicellular 

 with protoplasmic contents throughout, or 2-3 celled and only partially filled 

 with dense protoplasm. At first they were close together, but gradually 

 diverged and stood out as finger-like processes. In some cases they grew out 

 into long slender filaments, reaching a length of 76 {.i. 



Spores were finally taken from wheat of last season and floated on tap 

 water in a watch-glass in April. In about four days 40 per cent, had ger- 

 minated, showing various stages of development. The longer or shorter 

 promycelium was generally unicellular, but sometimes septate, and there 

 might be only one germinal tube from a cluster of spores or occasionally two, 

 and in one case each of the four spores in a ball germinated, producing conidia. 

 The conidia were generally 3-4, at first unicellular and cylindrical, but after- 

 wards becoming at least 1-2 septate. The earlier stages of germination show 

 the conidia close together and relatively short, then they diverge and grow 

 unequally. In some cases, one of the three or four may receive all the pro- 

 toplasm and grow out as an elongated slender curved filament, in others, all 

 the conidia may elongate and form variously curved and spreading filaments. 

 The behaviour of these conidia, even in water, indicates how their germ-tubes 

 may reach the host-plant, by growing stolon-like in the soil and penetrating 

 a suitable host, if they reach it at the proper stage (Plate V., C.) 



The conidia are formed by the splitting up of the promycelium at the apex 

 into several branches, which are direct prolongations of it, like the fingers on 

 the palm of the hand, although not all in the same plane. The conidia do not 

 become detached, as a rule, although I have occasionally seen a few separate, 

 truncate at the base and producing a slender germ-tube at the apex. 



The Flag smut of wheat is closely allied to the stem smut of rye, and the 

 germination of the latter is given here for comparison. Since Rye smut does 

 not occur in Australia, specimens were collected by P. Sydow in the neigh- 

 bourhood of Berlin on 21st July, 1907, and forwarded to me. The spores 

 were placed on a slide with tap water added on 13th September, or 54 days 

 after being gathered, and kept under a bell-jar. On the second day they 

 showed signs of germination, and on the third day they were germinating 

 freely and producing conidia at the apex of the germinal tube. The germinal 

 tube varied considerably in length, sometimes reaching 100 /< or more, and 

 at first was filled with protoplasmic contents. At the apex, a Avhorl of 2-6 

 cylindrical conidia were given off, generally 3-4. The germinal tube or pro- 

 mycelium is finally 4-5 septate and the contents in the lower portion of the 

 tube are transferred to the upper. The apical conidia are very variable in 

 size and shape. They are generally elongated, cylindrical, and either straight 

 or slightly curved. Sometimes they may become prolonged at the apex Avhile 

 still attached, into a tapering filament, reaching a length of 50 j.i or more. 



The germination of stem smut of Rve has also been studied by Kuehn, 

 Wolff, and Brefeld. 



According to Kuehn ^ the fertile spores readily germinate in water and 

 produce a longer or shorter unicellular germinal tube, which bears at its apex 

 a whorl, consisting of two to six cylindrical conidia. They sometimes unite 

 in pairs as in Tilletia, by means of a transverse bridge towards their upper 

 ends, and often germinate while still attached by putting forth a slender germ- 

 tube. 



