No. 5.] USTILAGINE.E 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 4ju to 

 35^.* 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, ya, 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 but 

 singly or in clusters on the various parts of the hosts. See 



* A ix, or micron, is one twenty-five thousandth of an inch. 



