74 British Uredinea and Ustilaginecs. 



to them by Continental botanists, we may use it when 

 writing or speaking in EngUsh. 



The promycelial spores very commonly produce second- 

 ary promycelial spores by budding. Hence we may speak 

 of primary and secondary promycelial spores. When these 

 promycelium spores continue many times to multiply them- 

 selves by budding, after the manner of Saccharomyces, 

 Uredine spermatia, etc., they may very well be called, 

 as Brefeld suggests, " yeast-spores " and " yeast-colonies." 

 The term " conidia " will be confined to that form of fruit 

 in Tubercinia and Entyloma which is produced in the air 

 from the mycelium in the living host-plant. 



Ustilago. — The germination of the spores of Ustilago 

 varies somewhat in different species. The commonest 

 type is that of U. segetimi, violacea, inaydis, kuhneana, 

 scabios(£, etc. 



U. segetiivi. — If a few spores be placed in a drop of 

 water, they will begin to evince signs of vitality in six or 

 eight hours. Germination occurs more rapidly in summer 

 than in winter, and in fresh spores than in those which 

 have been kept some months. At one point of its surface 

 the spore emits a germ-tube, which grows straight out- 

 wards, until it is from three to four times as long as the 

 spore is wide ; and under certain circumstances this tube 

 may, according to Kiihn, have the functions of a germ- 

 tube (Plate VII. Fig. 6), entering by its pointed extremity 

 the tissues of the host-plant. Normally, however, it becomes 

 divided by septa into from three to five compartments, 

 generally into four. This germ-tube is an outgrowth of 

 the endospore, which is pushed upward through the exo- 

 spore. It is from 30 to 40^ long, and from 4 to 5/1 broad 

 at its maturity. At first it is in direct communication with 

 the endospore, and the protoplasm therein contained passes 

 into the germ-tube and fills it. Adopting the phraseology 



