No. 5.] USTILAGINEE OF CONNECTICUT. 7 
ternal part of the fungus, making up the smutty masses visible 
to the naked eye, and are the characteristic and variable parts 
upon which species are based. The spores are usually so 
formed that at maturity they break out to the exterior of the 
host in a dusty mass that is easily scattered, thus securing 
their dispersal. In some species, however, they are embedded 
in the host so that they are liberated only on the rotting of the 
tissues, and sometimes they germinate in situ, and secure their 
dispersal by the formation of secondary spores of.a different 
nature. While easily seen in mass, the spores are really 
microscopic in size, varying according to species from 4p to 
35u-* They are usually subspherical or spherical, but vary 
to ovoid, ellipsoidal, or even oblong. Pressure often makes 
them more or less polyhedral, or irregularly so. They are 
generally simple, consisting of single separate cells; but are 
sometimes bound more or less permanently into spore balls, 
Figs. 7a, 10a. These spore balls may consist entirely of fer- 
tile cells (spores) or they may have an external coating (cor- 
tex) of sterile cells, Fig. 19, or an internal matrix of sterile 
cells or even of threads, Fig. 20. The spore walls may be 
smooth, or marked with minute spines (echinulations if sharp, 
verruculations if dull), or reticulated with a net-work of 
ridges or wings. In color they are hyaline, yellowish, red- 
dish or olive brown, violet, or purplish. Often the color is 
so deep that the spores are opaque or nearly so. Upon these 
variations the genera and species are chiefly classified, though 
on the whole the variations are not so great as with many 
of the other fungi. This is partly due to the fact that the 
spore-producing threads are not diversified*or permanent. 
In some few species, most frequently in the genus Enty- 
loma, the mycelium also gives rise to secondary spores called 
conidia. These are usually hyaline, elongated, ephemeral, 
and are produced originally on the exterior of the host, gener- 
ally from mycelial tufts protruding through the stomates and 
forming these conidia at their tips. Their object is to spread 
the smut over the host or to new hosts immediately. 
Sori are the evident masses of the spores that break out 
singly or in clusters on the various parts of the hosts. See 
* Au, or micron, is one twenty-five thousandth of an inch. 
