Chapter XVIII: Theories Continued--Weismann. De Vries, 392

Weismann's views have passed through various stages of remodeling,
392. The Evolution Theory published in 1904 is the best exposition
of his views, 392. His theory the field for much controversy.
Primarily a theory of heredity, 393. Weismann's theory
summarized, 393. Continuity of the germ-plasm the central idea
in Weismann's theory, 394. Complexity of the germ-plasm. Illustrations,
395. The origin of variations, 396. The union of
two complex germ-plasms gives rise to variations, 396. His extension
of the principle of natural selection--germinal selection,
397. The inheritance of acquired characters, 398. Weismann's
analysis of the subject the best, 398. Illustrations, 399. The
question still open to experimental observation, 399. Weismann's
personality, 400. Quotation from his autobiography, 401.
The mutation theory of De Vries, 402. An important contribution.
His application of experiments commendable, 403. The
mutation theory not a substitute for that of natural selection, 404.
Tendency toward a reconciliation of apparently conflicting views,
404. Summary of the salient features of the theories of Lamarck,
of Darwin, of Weismann, and De Vries, 405. Causes for bewilderment
in the popular mind regarding the different forms of the
evolution theory, 406.