But the modes of constitution, as of inheritance, are more complex, of course, than that one parent supplies the potential of one side, the other parent that of the other side. As regards inheritance, the maternal ovum comprises, I believe, the potential of the whole body, with the exception of the brain, the spinal-cord and the spinal nerves. But because the mother is descended from parents of both sex, and possesses, therefore, both Male and Female elements, the ovum must contain (as must every other cell) both male and female factors. These, it is conceivable, are grouped, by contrary polarities, into two areas, or hemispheres; an upper and a lower. Of these the upper is Male in inherency. It comprises the potentials of shoulders and spinal column which are fulcra of action, and of lungs and heart which are the _energising_ organs of Life. The lower hemisphere of the ovum is Female in inherency. It comprises the potentials of the pelvis, which is the cradle of Maternity, of the reproductive organs, which engender Life and the emotions, and of the digestive and assimilative organs, which engender vital processes. So too, because the male parent is likewise descended from parents of opposite sex, his contribution to offspring must also contain both male and female factors. But while the mother supplies, in the ovum, the potential of the whole body--face and head, trunk, limbs and vital organs, the father contributes the potential of the brain, the spinal cord and the spinal nerves only, which adapt the organism, by way of form and Consciousness, to environment. The limbs, which adapt it, by way of Motion, to environment, may be regarded as differentiations primarily of the brain and nervous system. The ovum is spheroidal; the sperm-cell rectilinear (following the rule that the line of Maleness is a straight one; that of Femaleness, a curve). And as in the spheroidal ovum, the factors of the opposite sexes, grouped into two areas, separate it into hemispheres of opposite sex-inherency, so in the rectilinear sperm-cell, we may surmise the factors of the two sexes to be grouped lengthwise, and to separate it thus into a male side and a female side. Such a sperm-cell penetrating the ovum, and developing laterally, further differentiates this into anterior, posterior and lateral areas. The two lateral developments of this potential brain and spinal cord and nerves eventually constitute the right and the left brain-hemispheres, and differentiate the body into right and left sides. The left brain-hemisphere, with its half of the spinal cord and nerves, is derived from the _male_ side of the sperm-cell; while the right brain-hemisphere, with its half of the spinal cord and spinal nerves, is derived from the _female_ side (by inheritance) of the sperm cell. Weismann describes the Germ-Plasm as being transmitted in the female line solely, from ovum of mother to that of daughter.