Thus it will be seen that, inasmuch as we have complex brands in which the number of cells are considerably increased, so have we “complex smuts” in which, instead of one cell, we have many. In the last instance the two genera associated together in this chapter agree. The spores in both are distinctly cellular, but in the last genus far more opaque and consolidated than in the first. Whilst it may be doubted whether the compound spores of _Polycystis_ are anything more than a number of individual spores with a gregarious habit, invested with an outer membrane, such a hypothesis cannot (as far as our individual examinations extend), be made to include _Tubercinia_. No doubt has yet been thrown on the genuine character of either of these genera. No _Uredo_ or _Æcidium_, no _Trichobasis_ or _Puccinia_ has been ascertained or suspected to appear as a prior or subsequent form. In their supposed integrity they offer an interesting study, and in their development a good subject for investigation. ------------------------------------------------------------------------ CHAPTER VIII. _RUSTS._ UNFORTUNATELY, this group of fungi contains species but too well known for their ravages amongst graminaceous plants, especially the cereals. “Corn rust,” as it is generally called, has a reputation little better than mildew, and it really deserves no better, for it is only another form of that pest of the farm, from the mycelium of which the corn-mildew is at length developed. There are two species very closely allied (doubtless only forms of the same species with different spores) which attack the leaves and culms of growing corn, and, bursting through the cuticle in the manner represented in Plate VII. fig. 141 (magnified), give a peculiar rusty appearance to the plant, as represented in Plate VII. fig. 140. One of these corn-rusts is botanically named _Trichobasis rubigo-vera_ (Lev.), or the “true rust _Trichobasis_;” the latter, which is the generic name, being a compound of two Greek words (_thrix_, a hair, and _basis_, a foundation), on account of the spores being at first furnished at their base with a short, thread-like peduncle, which at length falls away (Plate VII. fig. 142). The other Corn rust is _Trichobasis linearis_, or “line-like _Trichobasis_,” because the sori or pustules are linear, or lengthened out like a line; the spores nearly double the length of those of the other Corn rust (Plate VII. fig. 144), and not so bright in colour. By intermediate forms these two rusts pass insensibly the one into the other, so that it is sometimes difficult to distinguish them. Both have the spores clustered together in the pustules, at first (Plate VII. fig. 143) attached by their peduncles, but they soon become free, and are scattered like rust-powder over the plant. Adverting to the attack of rust upon the wheat crops to an unusual extent a few years since, the Rev. M. J.