Love seems to be primarily (and perhaps ultimately) an interchange of essences. The Protozoa—those earliest cells, the progenitors of the whole animal and vegetable kingdom—grow by feeding on the minute particles which they find in the fluid surrounding them. The growth continues, till ultimately, reaching the limit of convenient size, a cell divides into two or more portions; and so reproduces itself. The descendant cells or portions so thrown off are simply continuations, by division, of the life of the original or parent cell—so that it has not unfrequently been said that, in a sense, these Protozoa are immortal, since their life continues indefinitely (with branching but without break) from generation to generation. This form of reproduction by simple budding or division extends even up into the higher types of life, where it is sometimes found side by side with the later sexual form of reproduction, as in the case of so-called _parthenogenesis_ among insects. It is indeed a kind of virgin-birth; and is well illustrated in the vegetable world by the budding of bulbs, or by the fact that a twig torn from a shrub and placed in the ground will commonly grow and continue the life of the parent plant; or in the lower stages of the animal world, where, among many of the worms, insects, sponges, &c., the life may similarly be continued by division, or by the extrusion of a bud or an egg, without any sex-contact or sex-action whatever. This seems in fact to be the original and primitive form of generation; and it obviously depends upon _growth_. Generation is the superfluity, the ὕβρις, of growth, and connects itself in the first instance with the satisfaction of hunger. First hunger, then growth, then reproduction by division or budding. And this process may go on apparently for many generations without change—in the case of certain Protozoa even to hundreds of generations. But a time comes when the growth-power and energy decay, and the vitality diminishes[1]—at any rate, as a rule.[2] But then a variation occurs. Two cells unite, exchange fluids, and part again. It is a new form of nourishment; it is the earliest form of Love. It is a very intimate form of nourishment; for it appears that in general the nuclei themselves of the two cells are shared and in part exchanged. And the vitality so obtained gives the cells a new lease of life. They are in fact regenerated. And each partner grows again actively and reproduces itself by budding and division as before. Sometimes the two uniting cells will remain conjoined; and the joint cell will then generate buds, or in some cases enlarge to bursting point, and so, perishing itself, break up into a numerous progeny.[3]