=Increased number of the cotyledons.=--Although the presence of one or of two cotyledons in the embryo is generally accepted as a valuable means of separating flowering plants into two primary groups, yet, like all other means of discrimination, it occasionally fails, and, indeed, almost always requires to be taken in conjunction with some other character. There are cases among flowering plants where the embryo is homogeneous in its structure, there are others in which the number of the cotyledons is more than two. Thus, in some seeds of _Cola acuminata_ the cotyledons vary in number from two to five. I have not been able to ascertain precisely whether this multiplication of the cotyledons is characteristic of all the seeds of particular trees, or whether some only are thus affected. Some fruits that I examined bore out the latter view, as in the same pod were seeds with two, three, and four cotyledons respectively. I have also seen three cotyledons present in embryo-plants of _Correa_, _Crataegus Oxyacantha_, _Dianthus sinensis_, _Daucus Carota_, _Cerasus Lauro-cerasus_. De Candolle alludes to a case of the kind in the bean, and figures a species of _Solanum_ with three cotyledons.[420] Jaeger alludes to a similar instance in _Apium Petroselinum_;[421] Ehrenberg to one in the marigold (_Calendula_);[422] Reinsch to an analogous appearance in the beech (_Fagus_), associated with a union of the margins of two out of the three cotyledons, and of those of two out of the three leaves next adjacent.[423] This fusion seems frequently to accompany increase in the number of cotyledons. It was so in the _Correa_, and in the _Crataegus_ previously mentioned. Some of these cases may be accounted for by chorisis or by a cleavage of the original cotyledons, as happens, according to Duchartre,[424] in some Coniferae, which he considers to be improperly termed polycotyledonous. Whether this holds good in the Loranths, where (_Nuytsia_, _Psittacanthus_) an appearance of polycotyledony exists, is not stated. In the case of the rue (_Ruta_) figured by M. A. de Jussieu[425] this splitting of one cotyledon into two is sufficiently evident, as is also the case in the sycamore (_Acer pseudo-platanus_), seedlings of which may often be met with divided cotyledons. In other instances a fusion of two embryo plants may give rise to a similar appearance, as in the _Euphorbia_ and _Sinapis_ found by M. Alph. de Candolle (see _ante_, p. 56).