40 FUNGI, 
other with great difficulty. As might be anticipated, this has 
considerable effect on the contour of the spores, which in pul- 
verulent species are shorter, broader, and more ovate than in 
the compact species. If a section of one of 
the more compact sori be made, it will be 
seen that the majority of the spores are side 
by side, nearly at the same level, their apices 
forming the external surface of the sori, but 
it will not be unusual to observe smaller 
and younger spores pushing up from the, 
Fic. 22.—Psendospores bymenial cells, between the peduncles of 
of Pugeumia the elder spores, leading to the inference 
that there is a succession of spores produced in the same pulvi- 
nule. In Podisoma, a rather anomalous genus, the septate spores 
are immersed in a gelatinous stratum, and some authors have 
imagined that they have an affinity with the Tremellini, but 
this affinity is more apparent than real. The phenomena of 
germination, and their relations to Restelia, if substantiated, 
establish their claim to a position amongst the Pucemiai.* It 
seems to us that Gymnosporangium does not differ generically 
from Podisoma. In a recently-characterized species, Podisoma 
Ellisii, the spores are bi-triseptate. This is, moreover, peculiar 
from the great ‘deficiency in the gelatinous element. In another 
North American species, called Gymnosporangium biseptatum, 
Ellis, which is distinctly gelatinous, there are similar biseptate 
spores, but they are considerably broader and more obtuse. In 
other described species they are uniseptate. 
Ustinacinet.—These fungi are now usually treated as distinct 
from the Ceomacei, to which they are closely related.+ They 
are also parasitic on growing plants, but the spores are usually 
black or sooty, and never yellow or orange; on an average much 
smaller than in the Ceomacei. In Tilletia, the spores are 
spherical and reticulated, mixed with delicate threads, from 
* Cooke, ‘‘On Podisoma,” in ‘‘ Journal of Quekett Microscopical Club,”’ vol. ii. 
p. 255. 
+ Tulasne, ‘‘ Mémoire sur les Ustilaginées,” in ‘‘ Ann. des Sci, Nat.” (1847), 
vii. pp, 12 and 73. 
