Probably one of the chief objects, which the early herbalists had in view in writing their books, was to enable the reader to identify various medicinal plants. Nevertheless, until well into the sixteenth century, their drawings were so conventional, and their descriptions left so much to be desired, that it must have been an almost impossible task to arrive at the names of plants by their aid alone. The idea which suggests itself is that a knowledge of the actual plants was, in practice, transmitted by word of mouth, and that the herbals were only used as reference books, to ascertain the reputed qualities of herbs, with whose appearance the reader was already quite familiar. If this supposition is correct, it perhaps accounts for the very primitive state in which the art of plant description remained during the earlier period of the botanical renaissance. When we turn to the Aristotelian school, we find that the writings of Theophrastus include certain plant descriptions, which, although they seem somewhat rudimentary when judged by modern standards, are greatly in advance of those contained in the first printed herbals. The mediæval philosopher, Albertus Magnus, who, as we have already pointed out, was a follower of Aristotle and Theophrastus, also showed marked originality in his descriptions of flowers, and drew attention to a number of points which appear to have escaped the notice of many more recent writers. For instance, in describing the flower of the Borage he distinguished the green calyx, the corolla with its ligular outgrowths, the five stamens and the central pistil, though naturally he failed to understand the function of the latter organs. He observed that, in the Lily, the calyx was absent, but that the petals themselves showed transitions from green to white. He noticed the early fall of the calyx in the Poppy, and its persistence until the ripening of the fruit in the Rose. On the subject of floral æstivation, his observations were surprisingly advanced. He pointed out that the successive whorls of sepals and petals alternated with one another, and concluded that this was a device for the better protection of the flower. Albertus further classified the various forms of flower under three types:— 1. Bird-form (e.g. _Aquilegia_, _Viola_ and _Lamium_). 2. Pyramid- and Bell-form. 3. Star-form. When we leave the early Aristotelian botanists, and turn to those who studied the subject primarily from the medical point of view, we find a great falling off in the power of description. The accounts of the plants in the Materia Medica of Dioscorides, for example, are so brief and meagre that only those with the most marked characteristics can be identified with certainty.