74 British Uredinee and Ustilaginee. 
to them by Continental botanists, we may use it when 
writing or speaking in English. 
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. segetum, violacea, maydis, kiihneana, 
scabios@, etc. 
U. segetum.—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 4ou long, and from 4 to 5u 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 phraseologt, 
