Germination of Tclciitosporcs of Ustilao^inccE. 8 7 



known since 1807, when Prevost* figured not only the 

 promycelium, but the primary and secondary promycelial 

 spores. Mr. Berkeley,! in 1847, discovered the conjugation 

 of the primary spores, which was again more fully investi- 

 gated by Tulasne. % Kiihn § gives a full account of the 

 process. Since then nothing has been added to our know- 

 ledge of the subject, till Wolff || showed the method by 

 which the germ-tube enters the host-plant, and Brefeld If 

 investigated the further development of the spores in 

 nahrlosung. 



The spores do not germinate until they have been 

 placed in water for some considerable time, not before 

 forty-eight or fifty hours ; but often I have found them to 

 take a much longer period. They retain their germinative 

 power for two or three years, and one author says as long 

 as eight and a half years.** The process differs materially 

 from that previously described in the other genera. The 

 promycelial tube is emitted from a small germ-pore, but 

 very soon, as the tube increases in diameter, it causes the 

 epispore to split. Its length varies according to circum- 

 stances, its diameter being about 8/i. If it be given out 

 from a spore under water, at the bottom of the culture-drop, 

 it grows upwards until its apex reaches the air. As soon 

 as the promycelium has reached the air several tubercula- 

 tions appear upon its summit. The protoplasmic contents 

 of the spore are passed along the promycelium to its 

 extremity. If the promycelium happen to be a very long 

 one, then numerous septa occur from below upwards ; but, 



* Prevost, "Memoire sur la cause immediate de la Carie." 1807. 

 t Berkeley, " Propag. of Bunt," Trans. Roy. Hort. Soc. (1847), vol. ii. 

 p. 113. 



X Tulasne, " l'° Mem. sur les Ured. et les Ustilag." 1854. 



§ Kiihn, " Krank. der Kulturgew." 1859. 



II Wolff, " Der Brand des Getreides." 1874. 



^ Brefeld, loc. cit., pp. 146-163, t. xii., xiii. figs. 25-52. 



** Liebenburg, loc. cit. 



