In concluding our survey of vegetable evolution it may help us to a just perspective if we briefly review the main steps which the ancestors of angiosperms appear to have taken in their long upward journey. The accompanying diagrams (Fig. 384) will serve to recall the chief facts and conclusions already presented regarding the phylogeny of these highest plants, and also the ontogeny of modern types representing the supposed links in the series. In accordance with the "law of recapitulation" we find that the younger the stages the more they are alike, and that immature stages of the higher types correspond to mature stages of lower types, the youngest stage of each being a single cell like the supposed ancestor of all. This reproduces simply by fission, a process which is retained by all higher forms as growth by cell-division resulting in cell-rows, cell-plates, or cell-masses variously differentiated into tissues and ultimately, tissue-systems. Vegetative reproduction occurs also in these higher forms through the occasional separation of cells or cell-groups capable of independent life. Sexual reproduction appears with the fusion of two protoplasts to form one which afterward increases by division. In the aquatic forms the fusing protoplasts soon became motile and this motility is long retained in the male by their descendants while adapting themselves to a terrestrial life, and disappears finally when this is fully attained. The single protoplast resulting from the fusion of two gives a second unicellular beginning and thus the life-history of an individual becomes divided into a sexual and a non-sexual stage or generation. When the female protoplast remains attached to a plant in the sexual stage until after fertilization there results an egg-cell which becomes a non-sexual embryo if the connection be maintained so that the sexual generation may nurse the non-sexual. This new beginning, nursed by the more primitive stage, affords, it would seem, a good opportunity for the transition from life in water to life on land. Then, too, the nursing, when not excessive, both permits and encourages the highest development of the non-sexual generation. Finally, it nurses the nurse, and thus through ample provision for both nurse and nursling produces a seed well cared for in every way. This is the greatest achievement of the vegetable kingdom.