It is necessary to distinguish in the case of the nut between additional seeds or ovules, as just described, and the double, triple, or fourfold nuts that are occasionally met with, and which are the result either of actual multiplication of the carpels or of the continued development of some of the carpels which, under ordinary circumstances cease to grow (see _ante_, p. 364). In the case of a ripe nut with two seeds it might be impossible to tell whether the adventitious seed were the product of multiplication, or whether it belonged, in the first instance, to the same carpel as that producing the fellow-seed, or to a different and now obliterated ovary. In all probability, however, the second seed would be accounted for by the development of two seeds in one carpellary cavity. There is still another condition occasionally met with in the almond, and which must be discriminated from the more common multiplication of the seed, and which is the multiplication of the embryos within the seed, and which furnishes the subject of the succeeding paragraph. =Increased number of embryos.=--A ripe seed usually contains but a single embryo, although in the ovular state preparation is commonly made for more; and, indeed, in certain natural orders plurality of embryos in the same seed does occur, as in _Cycadeae_ and _Coniferae_. In the seeds of the orange (_Citrus_), in those of some _Euphorbiaceae_, &c., there are frequently two or more additional embryos. A similar occurrence has been recorded in the mango, for a specimen of which I am indebted to the Rev. Mr. Parish, of Moulmein.[419] Plurality of embryos has also been observed in-- Raphanus sativus. *Citrus Aurantium! Diosma, sp. Hypericum perforatum. Triphasia aurantiaca. *AEsculus Hippocastanum! Euonymus latifolius. *Mangifera indica! Eugenia Jambos. Amygdalus vulgaris! Vicia, sp. Cassia, sp. *Viscum album! Daucus Carota. Ardisia serrulata! Cynanchum nigrum. fuscatum. Euphorbia rosea. Coelebogyne ilicifolia. Allium fragrans. Funckia, sp. Carex maritima. Zea Mays. See Schauer's translation of Moquin-Tandon, 'El. Terat. Veget.,' p. 245, adnot., and 'Al. Braun Polyembryonie.'