SMUT FUNGI— USTILAGINES 



255 



and these again may continue to multiply themselves many 

 times by budding, after the manner of yeast-spores, which is 

 the term applied to them by Brefeld, but liable to misinter- 

 pretation. In order the better to comprehend the process, it 

 may be detailed as observed in Tilletia (Fig. 120). This parasite 

 produces its teleutospores within the grains of wheat, and is 

 known to farmers as "bunt." 

 The appearance of the grains 

 externally is very little 

 changed, but slightly darkened 

 in colour, and when crushed 

 are seen to be filled with 

 a sooty, rather fetid powder. 

 These teleutospores are globose, 

 dark coloured, almost black, 

 and the surface minutely 

 reticulated. When placed in 

 water they germinate in about 

 forty-eight hours. A germ- 

 tube is emitted from a very 

 small germ-pore, but it does 

 not attain any considerable 

 length; and this germ-tube 

 constitutes the promycelium, 

 into which the contents of the 

 parent spore pass and retreat 

 to the extremity, and are 



Flo. 120. — Tilletia spores in germination. 

 a, producing a promycelium, p ; b, 

 primary spore with promycelium, p, 

 bearing couidia, of which some are 

 conjugating ; c, conjugated gonidia in 

 germination, -with secondary gonidiuni 

 at s'. After De Bary. 



shut off 



by the formation 

 of a transverse septum. Tuberculations are soon manifest 

 about the summit, and these by lengthening become the 

 first promycelial spores. They are thread - like, curved, 

 and colourless, to the number of from four to a dozen. 

 When fully developed they are cut off from, the pro- 

 mycelium by a septum at the base. Soon afterwards these 

 primary spores will be seen to connect themselves, mostly in 

 pairs, by a transverse connective, performing an act of conjuga- 

 tion. These conjugated primary spores are often separated 

 from the promycelium, but they may remain for a long time 

 attached. In due time budding takes place, and the buds 

 become converted into cylindrical curved secondary spores, the 



