13. Plasmic Metabolism. The innumerable forms of plant and animal life arose from the ceaseless transformation of the living substance in which the most important factors are the physiological functions of variation and heredity.
14. Phytogeny. All plants and animals form a single genealogical tree rooted in the Monera.
15. Anthropogeny. The position of man in nature is now fully understood. He has all the characteristics of the vertebrates and mammals and developed out of this class in the later tertiary period.
16. Pithecoid Theory. Man is most nearly related to the tailless apes, but is not descended from any of the existing forms. On the contrary, the common ancestors of all the anthropoid apes and man are to be looked for in the earlier extinct species of old world apes (Pithecanthropus).
17. Athanism. The soul consists of the totality of cerebral functions. This soul or thought organ in man, a certain area of the cerebral cortex, acts in accordance with the same laws of psychophysics as in the other mammals. This function of course ceases at death, so it is nowadays utterly absurd to believe in "the personal immortality of the soul."
18. Indeterminism. The human will, like all other functions of the brain (sensation, imagination, ratiocination), is dependent upon the anatomy of this organ and is necessarily determined by the inherited and acquired characteristics of the individual brain. The old doctrine of "free will" is therefore seen to be untenable and must give way to the opposite doctrine of determinism.
19. God. If by this ambiguous term is understood a personal "Supreme Being", a ruler of the cosmos who, after the manner of men, thinks, loves, generates, rules, rewards, punishes, etc., such an anthropomorphic God must be relegated to the realm of the mystical fiction, no matter whether this personal God be invested with a human form or regarded as an invisible spirit or as a "gaseous vertebrate." For modern science the idea of God is tenable only so far as we recognize in this "God" the ultimate unknowable cause of things, the unconscious hypothetical "first cause of substance."
20. Law of Substance. The older chemical law of the conservation of matter (Lavoisier, 1789) and the more recent physical law of the conservation of energy (Mayer, 1842) were later (1892) by our Monism united into a single great universal law, for we recognized matter and energy (body and spirit) as inseparable attributes of substance (Spinoza).