Whole or partial development may thus be dependent on the power of regulation contained in the intimate polar-bilateral structure of the protoplasm. Where this is so, the regulation and the differences in development are both connected with the chief relations of symmetry. The development becomes a half or a quarter of the normal because there is only one-half or one-quarter of a certain structure present, one-half or one-quarter with regard to the very wholeness of this structure; the development is whole, in spite of disturbances, if the intimate structure became whole first. We may describe the “wholeness,” “halfness,” or “quarterness” of our hypothetic structure in a mathematical way, by using three axes, at right angles to one another, as the base of orientation. To each of these, *x*, *y*, and *z*, a certain specific state with regard to the symmetrical relations corresponds; thence it follows that, if there are wanting all those parts of the intimate structure which are determined, say, by a negative value of *y*, by minus *y*, then there is wanting half of the intimate structure; and this halfness of the intimate structure is followed by the halfness of organogenesis, the dependence of the latter on the intimate structure being established. But if regulation has restored, on a smaller scale, the whole of the arrangement according to all values of *x*, *y* and *z*, development also can take place completely (Fig. 7). [Illustration: Fig. 7.--Diagram illustrating the intimate Regulation of Protoplasm from “Half” to “Whole.” The large circle represents the original structure of the egg. In all cases where cleavage-cells of the two-cell stage are isolated this original structure is only present as “half” in the beginning, say only on the right (+*y*) side. Development then becomes “half,” if the intimate structure remains half; but it becomes “whole” (on a smaller scale) if a new whole-structure (small circle!) is formed by regulatory processes.] I am quite aware that such a discussion is rather empty and purely formal, nevertheless it is by no means without value, for it shows most clearly the differences between what we have called the intimate structure of germs, responsible only for the general symmetry of themselves and of their isolated parts, and another sort of possible structure of the egg-protoplasm which we now shall have to consider, and which, at the first glance, seems to form a serious difficulty to our statements, as far at least as they claim to be of general importance. The study of this other sort of germinal structure at the same time will lead us a step farther in our historical sketch of the first years of “Entwickelungsmechanik” and will bring this sketch to its end. ON SOME SPECIFICITIES OF ORGANISATION IN CERTAIN GERMS