Gcnuinatioii of Tdcutospores of Ustilaginccr. 95 



the six spores generally only three germinate, and pro- 

 duce at their distal extremities secondary spores similar in 

 size and shape to themselves.* 



U. priimdicola, Magnus. — Pirotta t found that the fresh 

 ripe spores germinated in water in about ten hours, by 

 emitting a short cylindrical promycelium, which at its 

 extremity gave off three or four branches that became 

 spores, measuring from 9 to 18^1 in length, and from 4 

 to 9/.J in width. These, while still attached, produced 

 secondary spores from their ends. The secondary spores 

 germinated by the protrusion of a germ-tube (about 3// 

 wide, and from 10 to 20 times as long as the spore), into 

 which the protoplasm migrated. Lateral conjugation was 

 occasionally observed. 



This species occurred in 1884, in Rev. C. Wolley Dod's 

 garden, on P . farinosa. In August of that year I received 

 some specimens from Mr. Dod. The spores germinated 

 readily in water, and emitted short promycelia, which bore 

 a cluster of promycelial spores as figured by Pirotta. I 

 found that no spore-formation took place unless the end of 

 the promycelium grew irt the air. If a spore germinated 

 at the bottom of a drop of water, the promycelium grew 

 upwards through the water until it reached the air. In 

 these cases the lower part of the promycelium became 

 emptied of its protoplasm and septate, just as one sees in 

 Tilletia (Plate VII. Fig. 26, 27). The promycelial spores 

 varied from 12 to 20/( in length, and were 4 or ^yi in width 

 (Figs. 28, 29, 30). After keeping the promycelial spores 

 in nahrlosung for two hundred and sixty-four hours, no 

 further spore-formation was observed ; but the}' became 

 septate and nucleate (Fig. 29). 



MelanotcBiiimn. — The mycelium is principally inter- 



* Prillieux, loc. cit. 



t Pirotta, " Nuovo Giornale Bot. Ital.," vol. xii. (1881), pp. 235-239, t. vi. 



