From this account, then, it is extremely probable that the _Æcidium_ of the berberry enters into the cycle of existence of _Puccinia graminis_, and, if this be true, wherefore should not other species of _Puccinia_ be related in like manner to other _Æcidia_? This is the conclusion to which many have arrived, and, taking advantage of certain presumptions, have, we fear, rashly associated many such forms together without substantial evidence. On the leaves of the primrose we have commonly a species of _Æcidium_, _Puccinia_, and _Uromyces_ nearly at the same time; we may imagine that all these belong to one cycle, but it has not yet been proved. Again, _Uromyces cacaliæ_, Unger, _Uredo cacaliæ_, Unger, and _Æcidium cacaliæ_, Thumen, are considered by Heufler[a] to form one cycle. Numerous others are given by Fuckel,[b] and De Bary, in the same memoir from which we have already cited, notes _Uromyces appendiculatus_, Link., _U. phaseolorum_, Tul., and _Puccinia tragopogonis_, Ca., as possessing five kinds of reproductive organs. Towards the end of the year, shortly stipitate spores appear on their stroma, which do not fall off. These spores, which do not germinate till after a shorter or longer winter rest, may conveniently be called resting spores, or, as De Bary calls them, _teleutospores_, being the last which are produced. These at length germinate, become articulated, and produce ovate or kidney-shaped spores, which in their turn germinate, penetrating the cuticle of the mother plant, avoiding the stomates or apertures by which it breathes. After about two or three weeks, the mycelium, which has ramified among the tissues, produces an _Æcidium_, with its constant companion, spermogonia--distinct cysts, that is, from which a quantity of minute bodies ooze out, often in the form of a tendril, the function of which is imperfectly known at present, but which from analogy we regard as a form of fruit, though it is just possible that they may be rather of the nature of spermatozoids. The _Æcidia_ contain, within a cellular membranous sac, a fructifying disc, which produces necklaces of spores, which ultimately separate from each other in the form of a granular powder. The grains of which it is composed germinate in their turn, no longer avoiding the stomates as before, but penetrating through their aperture into the parenchym. The new resultant mycelium reproduces the _Uredo_, or fifth form of fructification, and the _Uredo_ spores fall off like those of the _Æcidium_, and in respect of germination, and mode of penetration, present precisely the same phenomena. The disc which has produced the _Uredo_ spores now gives rise to the resting spores, and so the cycle is complete.[c]