This shows that the cold had affected not only the wing-primordia of the parental pupæ, but the germ-plasm as well, and at the same time that this latter variation was less marked than that of the determinants of the wing-rudiments. This gives rise _to an appearance_ of the transmission of acquired characters. In the case of many of these cold-aberrations in Lepidoptera the cold gives rise to variations, but does so not by creating anything new, but by giving the predominance to primary constituents which have long been present, but are usually suppressed, and so it is also among the plants. I have in mind, for instance, the interesting experiments of Vöchting on the influence of light in the production of flowers in phanerogams. These showed that the common balsam (_Impatiens noli me tangere_) produces its familiar open flowers in a strong light, but in weak light only bears small, closed, so-called 'cleistogamous' flowers. But it would be utterly erroneous to suppose that the strong or weak light is the real cause, the _causa materialis_, of these two forms of flowers: the degree of illumination is merely the stimulus which provokes one or other of the primary constituents to development, both kinds being present in the constitution of the plant. As has long been known, the balsam normally possesses two kinds of flowers, and the slumbering primary constituents of these are so arranged that the open flowers develop where there is a prospect of insect visits and cross-fertilization, that is, in sunny weather or in a strong light, while closed and inconspicuous flowers adapted for self-fertilization develop in weak light, that is, in shady places and in concealed parts of the plant, where insect visits are not to be expected. [Illustration: FIG. 129. _A_, an aberration of _Arctia caja_, produced by low temperature. _B_, the most divergent member of its progeny. After E. Fischer.]