The many organs by means of which our human organism accomplishes its manifold movements are just the same as in the apes, and the mechanism of their action is in no way different. The same two hundred bones, in the same order and composition, form our internal bony skeleton; the same three hundred muscles effect our movements. The differences we find in the form and size of the various muscles and bones (and which are, as is well known, also found between lower and higher races of men) are due to differences in growth in consequence of divergent adaptation. On the other hand, the complete agreement in the construction of the whole motor apparatus is explained by heredity from the common stem-form of the apes and men. The most striking difference between the movements of the two is due to man's adaptation to the erect posture, while the climbing of trees is the normal habit of the ape. However, it is unquestionable that the former is an evolution from the latter. A double parallel to this modification is seen in the jerboa among the ungulates, and in the kangaroo among the marsupials. Both these, in springing, use only the strong hinder extremities, and not the weaker fore-limbs; as a result of this their posture has become more or less erect. Among the birds we have an analogous case in the penguins (_aptenodytes_); as they no longer use their atrophied wings for flight, but only in swimming, they have developed an erect posture when on land. The human will is also not specifically different from that of the ape or any other mammal; and its microscopic organs, the neurona in the brain and the muscular cells in the flesh, work with the same forms of energy, and are similarly subject to the law of substance. Hence it is immaterial for the moment whether one believes in the freedom of the will according to the antiquated creed of indeterminism, or whether one holds it to be refuted scientifically by the arguments of modern determinists; in either case the acts of the will and voluntary movements follow the same laws in man as in the ape. The high development of the function in civilized man, the ample differentiation of speech and morality, art and science--in a word, the ethical significance of the will for higher culture--is in no way discordant to this monistic and zoologically grounded conception. In the lower races these privileges of the civilized will are only found in a slight degree, and some of them are wholly wanting among the lowest races. The distance between the lowest savage and the most civilized human being is greater, in this respect also, than that which separates the savage from the anthropoid ape. However, I refer the reader to the remarks I made at the close of the seventh chapter of the _Riddle_ on the problem of the freedom of the will and the infinite literature relating thereto. The reader who desires to go further into this subject will find it well treated in the works of Traugott Trunk (1902) and Paul Rée