Living plants suffer considerably from the predations of parasitic species, and foremost amongst these in importance are those which attack the cereals. The corn mildew and its accompanying rust are cosmopolitan, as far as we know, wherever corn is cultivated, whether in Australia or on the slopes of the Himalayas. The same may also be said of smut, for _Ustilago_ is as common in Asia and America as in Europe. We have seen it on numerous grasses as well as on barley from the Punjab, and a species different from _Ustilago maydis_ on the male florets of maize from the same locality. In addition to this, we learn that in 1870 one form made its appearance on rice. It was described as constituting in some of the infested grains a whitish, gummy, interlaced, ill-defined, thread-like mycelium, growing at the expense of the tissues of the affected organs, and at last becoming converted into a more or less coherent mass of spores, of a dirty green colour, on the exterior of the deformed grains. Beneath the outer coating the aggregated spores are of a bright orange red; the central portion has a vesicular appearance, and is white in colour.[Z] It is difficult to determine from the description what this so-called _Ustilago_ may be, which was said to have affected a considerable portion of the standing rice crop in the vicinity of Diamond Harbour. Bunt is another pest (_Tilletia caries_) which occupies the whole farinaceous portion of the grains of wheat. Since dressing the seed wheat has been so widely adopted in this country, this pest has been of comparatively little trouble. Sorghum and the small millets, in countries where these are cultivated for food, are liable to attacks from allied parasites. Ergot attacks wheat and rice as well as rye, but not to such an extent as to have any important influence upon the crop. Two or three other species of fungi are sometimes locally troublesome, as _Dilophospora graminis_, and _Septoria nodorum_ on wheat, but not to any considerable extent. In countries where maize is extensively grown it has not only its own species of mildew (_Puccinia_), but also one of the most enormous and destructive species of _Ustilago_. A singular parasite on grasses was found by Cesati in Italy, in 1850, infesting the glumes of _Andropogon_.[a] It received the name of _Cerebella Andropogonis_, but it never appears to have increased and spread to such an extent as was at first feared.