forms are of very local occurrence. The most beautiful of all, the _ornatissima_, is found only in Jemtland, the _aurobadia_ only in Sodermanland, the anopetala_ in other localities in the same country, the _roseola_ near Stockholm, and the yellow _lutescens_ in Finmarken. The researches of Wittrock included only a small number of elementary species, but every one who has observed the violets in the central parts of Europe must be convinced that many dozens of constant forms of the typical _Viola tricolor_ might easily be found and isolated. We now come to the field pansy, the _Viola arvensis_, a very common weed in the grain-fields of central Europe. I have already mentioned its small corolla, surpassed by the lobes of the calyx and its capacity of self-fertilization. It has still other curious differentiating characters; the pollen grains, which are square in _V. tricolor_, are five-sided in _V. arvensis_. Some transgressive fluctuating variability may occur in both cases through the admixture of pollen-grains. Even three-angled pollen grains are seen sometimes. Other marks are observed in the form of the anthers and the spur. There seem to be very many local subspecies [45] of the field-pansy. Jordan has described some from the vicinity of Lyons, and Wittrock others from the northern parts of Europe. They diverge from their common prototype in nearly all attributes, the flowers not showing the essential differentiating characters as in the _V. tricolor_. Some have their flower-stalks erect, and in others the flowers are held nearly at right angles to the stem. _V. pallescens_ is a small, almost unbranched species with small pale flowers. _V. segetalis_ is a stouter species with two dark blue spots on the tips of the upper petals. _V. agrestis_ is a tall and branched, hairy form. _V. nemausensis_ attains a height of only 10 cm., has rounded leaves and long flower-stalks. Even the seeds afford characters which may be made use of in isolating the various species. The above-mentioned elementary forms belong to the flora of southern France, and Wittrock has isolated and cultivated a number of others from the fields of Sweden. A species from Stockholm is called _Viola patens_; _V. arvensis curtisepala_ occurs in Gotland, and _V. arvensis striolata_ is a distinct form, which has appeared in his cultures without its true origin being ascertained. The alpine violets comprise a more widespread type with some local elementary species [46] derived exactly in the same way as the tricolored field pansies. Summarizing the general result of this description we see that the original species _Viola tricolor_ may be split up into larger and lesser groups of separate forms. These last prove to be constant in pedigree-cultures, and therefore are to be considered as really existent units. They are very numerous, comprising many dozens in each of the two larger subdivisions.