170 MASSACHUSETTS AGRICULTURE. 



represents the spores of the rye-smut, which are somewhat 

 larger than those of the onion-smut ; and instead of there being, 

 as is most frequently the case with the last-named fungus, one 

 central spore, there are usually two or three clustered together. 

 Figs. 1 and 2 represent the rye as it appears when attacked 

 by Urocystis occulta. The fungus generally affects the stalk 

 of the ear so that, as the disease advances, the ears fall over 

 by their own weight, the stalk, which has been burst open by 

 the disease, not being strong enough to support them. This 

 drooping of the ears is very characteristic, and by it the 

 presence of the disease in a field of rye can be recognized 

 even at some little distance. 



The genus Urocystis, as generally defined, differs from 

 Ustilago, to which the corn-smut belongs, by the presence of 

 accessory spores, as we have described. Thecaphora, a rather 

 rare genus, of which the only American representative, growing 

 on a grass-like plant, is Thecaphora aterrima Tul, found by 

 Professor C. E. Bessey on a species of Carex at Ames, Iowa, 

 has spores united in clusters like the central spores of Urocystis 

 occulta, fig. 3, but destitute of accessory spores. Of the 

 species of Urocystis, besides U. Cepulce, found on onions, and 

 U. occulta, already described on rye, there is a third species 

 common in New England, U. pompholigodes, found on the wood 

 anemone, in the stalks and leaves of which it produces blackish 

 purple swellings. The two last-named species are also found 

 in Europe, but U. Cepulm is found only in America. The 

 question arises, Where can U. Cepulaz, the onion-smut, 

 originally have come from? Certainly not from Europe, for 

 it is unknown there. Then how does it happen that, on a 

 cultivated plant introduced from Europe, there is found a new 

 and peculiar fungus which, as far as we know, has never been 

 found on any plant native to America? Spontaneous genera- 

 tion is, of course, in the present state of science, quite insup- 

 posable, nor can we say that the Urocystis on onions is only a 

 variety of that found on rye or the wood anemone, for apart 

 from what seem to us specific anatomical differences, it is true 

 that the species of Urocystis on rye and the wood anemone are 

 as common, or more common, in Europe than in America, and 

 yet no smut is found on the onion in Europe which comes 

 from the same stock as our own. 



