68 British Uredinee and Ustilaginee. 
nected with the remains of the spore-forming hyphe. At 
maturity these spores do not break up into dusty masses 
like Ustilago, but remain as compact colonies embedded in 
the tissues of the host-plant. Each spore has two coats, 
and contains coarse protoplasm. The outer coat is some- 
times gelatinous at its maturity. 
Urocystis.—-The process has been studied by Kiihn,* 
De Bary,t Wolff,f and Winter§. The spore-forming 
hyphz become swollen at their ends ; two or more of these 
branch and wind themselves together, generally in a spiral 
manner, so as to form a glomerulus, and then, becoming 
highly gelatinized, they are quite indistinguishable from 
each other. In JU. occulta, Wolff considers that they have 
a common investing membrane. At the same time, other 
branches are given off from the spore-forming hyphe, 
which apply themselves to the outside of the glomerulus 
(Plate V. Figs. 13, 14, 15). As Winter points out, this 
might be looked upon as a sexual act, the central spiral 
branches of the glomerulus being the carpogonium, and the 
external enveloping branches the pollinodium ; but there 
is no proof that this is really a sexual act, especially as 
similar conditions occur in the spore-formation of various 
Ustilaginez, and in Geminella, in which no sexuality 
occurs. The spores are formed entirely from the gelatinized 
central glomerulus, and, as De Bary first showed, the pseudo- 
spores are formed by the outer branches. Prillieux || con- 
siders that the spores of Urocystis are formed in a similar 
manner to those of Sorosporium. The details of his obser- 
vations are given on the plate which accompanies his paper. 
* Kiihn, loc. cit., pp. 78, 79. 
+ De Bary, ‘‘ Morph, und Physiol.,” p. 125. 
t Wolff, Bot. Zeitung, 1873 ; “ Der Brand des Getreides,” 1874. 
§ Winter, Flora, 1876, ‘‘ Ustilagineen.” 
|| Prillieux, ‘‘Sur la formation et la germination des Spores des Urocystis,” 
Ann. des Science Nat., 6° sér., Bot., vol. x. pl. i, 
