The organism, therefore, does not grow simply by the accretion of material, but, having attained a certain limit of size, it divides or reproduces. In the lowest plants and animals this process of division is simple: either the organism (unicellular or multicellular) divides itself into two approximately equal parts or it divides into a number of such parts. The first process is represented by the reproduction of a bacterium or an _Amœba_, or by the division of a Planarian worm; the second is represented by the division (in many Protozoa, for instance) of the whole organism into a number of spores. Fundamentally the two processes are alike: the simple, binary division of the Bacterium is followed at once by growth by accretion, while in brood-formation (the cases of multiple division) the parent cell divides, and then each of the daughter-cells divide, and so on for several generations. After the completion of these divisions the brood-cells grow by accretion to their normal size. It is meaningless, in the light of our previous discussion, to say that the individuality of the mother-cell “is merged in that of the daughter-cells.” But we may believe that a _Paramœcium_ possesses some degree of consciousness. Does it possess personality--that is, the feeling of isolation from the rest of the universe, and the feeling of oneness with its own past-memory or conscious duration? If so, its personality, when it divides, becomes one with that of its daughter-cells. Or is its personality and conscious past that also of its sister-cells, and also that of the no longer existent mother-cell, and the cell of which this in its turn was a part? We must remember that such an organism as a _Paramœcium_ shows in its behaviour most of the signs of intelligence; that the parts into which it divides when it reproduces are equally developed; and that the process of division may not interrupt the conscious duration of either part. Is there a common personality, or oneness of consciousness, of all the organisms of this kind which are descended from the same individual? Reproduction by division, simple or multiple, does not proceed indefinitely in the case of the unicellular organisms. Sooner or later there is a limit, and the cell is then no longer able to continue dividing. Conjugation then occurs in one of many modes. Essentially two organisms come into contact and their nuclei fuse, or rather some of the material of one nucleus is transferred to the other. The cells then separate and reproduction by division begins again.