Mitosis is a phenomenon taking place in the protoplasm. Therefore, it would be inadequate to consider it without any reference to protoplasm. It would be rather dangerous to consider mitosis solely apart from protoplasm. Thus, for the model-building of mitosis, it seems that first a model protoplasm is built and then a model mitosis, which is conformable with the former. Further, it would be inadequate to regard mitosis, which is of compound form, as the earliest type of division. Mitosis as a compound division must be an advanced form and must have appeared in the course of protoplasmic evolution. Thus, we have to build a model of protoplasmic evolution, too. In dealing with protoplasmic evolution, it is most important to consider the question of what factors lie at the basis of evolutionary development. In our model-building study, we assume in particular that there are peculiarities of the protoplasm exhibited by the behaviour of the forms following the law of dispairing (Paper I, Kuwada, 1963) and that there are regulations as responses to internal as well as external conditions. In the present paper, remarks on these points will be given in model forms. Division and syndesis are considered in Section I, both being taken as phenomena that follow the law of dispairing. Sexuality as a result of regulation is the subject of Section II. A brief sketch of our models of protoplasm and protoplasmic evolution will be given in Section III.