The field is covered with the myriad spores of a rust of a nearly spherical shape, brownish in colour, and here and there one with a short transparent colourless stalk or pedicel. This is the violet rust (_Trichobasis Violarum_, B.), very common all through the summer and autumn, generally on the under surface of the leaves of violets, in woods and hedgerows. Should it so happen that the spores when placed under the microscope are found to be two-celled, it will prove that instead of a rust, or _Trichobasis_, being under examination, a brand, or _Puccinia_, has been found, which is almost equally common, and which may, without such a test, be easily mistaken for a rust. According to the theory of di-morphism, this is the higher form or complete fruit of the same fungus, which in its simple-celled state is called _Trichobasis Violarum_. A similar circumstance may befall the student in examining the rust of labiate plants (_Trichobasis Labiatarum_, Lev.), which occurs on different species of mint, especially the water-mint, about the month of August. We have found a few of the two-celled spores of the _Puccinia_ imbedded in the pustules of this rust almost constantly, whilst the one-celled spores are not uncommon in the pustules of what is regarded as the true mint brand (_Puccinia Menthæ_, P.). In spring the young leaves of the periwinkle (_Vinca major_) will, in some situations, become thickened considerably, and ultimately browned on both faces with the pustules of a rust (_Trichobasis Vincæ_), which though covered with a conidioid dust are often very tardy in bursting the epidermis. It is almost impossible, after the pustule is ruptured, to find one in which the bilocular spores of _Puccinia_ (fig. 132) are not largely intermingled with the unilocular spores of the “rust” (Plate VI. fig. 131). Later in the season by two or three months, other leaves of the same plants will be found occupied by the smaller and more widely scattered pustules of _Puccinia Vincæ_, in which the unilocular spores of the “rust” will seldom be found. In this instance the leaves are scarcely thickened, and the colour of the spores is much darker. The under surface of the leaves is commonly alone occupied, and corresponding paler spots on the upper surface indicate the presence of the parasite beneath. The garden and field bean is liable in some seasons to become quite rust-coloured in consequence of the profusion of spores with which the leaves and stems are covered, from the bean rust (_Trichobasis Fabæ_, Lev.), which in like manner is considered as the simple stage or form of the bean brand (_Puccinia Fabæ_, Lk.). If the legumes are also examined, a few pustules will sometimes be found on them. Beans thoroughly infected with this rust or brand are seldom of much service in either field or garden.