=Increased number of ovules or seeds.=--This appears not to be of very frequent occurrence, at least in those plants where the number of these organs is normally small; where, as in _Primula_, the ovules and seeds are produced in large quantities, it is not practicable to ascertain whether the number be augmented or not in any particular case. Very probably, the attachment or source of origin of the ovules determines, in some measure, their number. Thus, in the case of marginal placentation the number must be limited by the narrow space from which they proceed, whereas in parietal and free central placentation the ovules are generally numerous. In the latter case, however, it will be remembered that solitary ovules are not rare. An increased number of ovules is generally remarked in conjunction with some other change, such as a foliaceous condition of the carpel, in which the margins are disunited. In such cases the ovules may occupy the margin or may be placed a short distance within it, as in the case of some open carpels of _Ranunculus Ficaria_,[417] and in which two ovules were borne in shallow depressions on the upper or inner surface of the open carpel and supplied with vascular cords from the central bundle or midrib. The outer coating of the ovule here contained barred or spiral fusiform vessels derived from the source just indicated. In the very common cases where the pistil of _Trifolium repens_ becomes foliaceous (see Frondescence), the outer ovules are generally two or more instead of being solitary. So, also, in the Rose with polliniferous ovules (see p. 274). Among _Umbelliferae_ affected with frondescence of the pistil a similar increase in the number of ovules takes place. It will be borne in mind that in most, if not all, these cases the structure of the ovule is itself imperfect.[418] What are called in popular parlance double almonds or double nuts (_Corylus_) are cases where two seeds are developed in place of one. In the 'Revue Horticole,' 1867, p. 382, mention is made of a bush which produces these double nuts each year--in fact, it never produces any single-seeded fruit. The plant was a chance seedling, perhaps itself the offspring of a double-seeded parent. It would be interesting to observe if the character be retained by the original plant, and whether it can be perpetuated by seed or by grafting.