_Are the Principles of the Selection Theory Mechanical?_ p. 645.
Refutation of Von Hartmann’s views, 645. Variability, 646. The
assumption of unlimited variability no postulate of the selection
theory, 647. The acknowledgment of a fixed and directed variability
does not necessitate the assumption of a phyletic vital force, 647.
Heredity, 657. Useful modifications do not occur only singly, 657.
New characters appearing singly may also acquire predominance, 659.
A mechanical theory of heredity is as yet wanting, 665. Haeckel’s
“Perigenesis of the Plastidule,” 667. Correlation, 670. The “specific
type” depends upon the physiological equilibrium of the parts of the
organism, 671. The theoretical principles of the doctrine of selection
are thus mechanical, 675. Importance of the physical constitution
of the organism in determining the quality of variations, 676. All
individual variability depends upon unequal external influences, 677.
Deduction of the limitability of variation, 682. Deduction of local
forms, 686. Parallelism between the ontogenetic and the phyletic vital
force, 687. The two are inseparable, 690.