from social structures, from cosmic, natural and
human history, much of it deduced by analogy, were jumbled together in
a fashion which seems amazing to us now, though common enough thirty
years ago. It was not a wild hypothesis in 1888, its real date, but its
repeated republication (in the original and in the works of other
writers who accepted it as authoritative) since 1903 has done much to
discredit sociology with biologists and, what is more serious, to muddle
ideas about sex and society.

In 1903, Weismann's theory of the continuity of the germplasm was ten
years old. De Vries' experiments in variation and Mendel's rediscovered
work on plant hybridization had hopelessly undermined the older notion
that the evolution or progress of species has taken place through the
inheritance of acquired characters--that is, that the individuals
developed or adapted themselves to suit their surroundings and that
these body-modifications were inherited by their offspring. As pointed
out in Chapter I, biologists have accepted Weismann's theory of a
continuous germplasm, and that this germplasm, not the body, is the
carrier of inheritance. Nobody has so far produced evidence of any trace
of any biological mechanism whereby development of part of the body--say
the biceps of the brain--of the individual could possibly produce such a
specific modification of the germplasm he carries as to result in the
inheritance of a similar development by his offspring.

Mendel's experiments had shown that the characters we inherit are units
or combinations of units, very difficult to permanently change or
modify. They combine with each other in all sorts of complicated ways.
Sometimes one will "dominate" another, causing it to disappear for a
generation or more; but it is not broken up. These characters have a
remarkable way of becoming "segregated" once more--that is, of appearing
intact later on.

While it follows from Weismann's theory that an adaptation acquired by
an individual during his lifetime cannot be transmitted to his
offspring, it remained for De Vries to show authoritatively that
evolution can, and does, take place without this. Once this was
established, biologists cheerfully abandoned the earlier notion. Lester
Ward and the biologists of his day in general not only believed in the
transmission of acquired characters, but they filled the obvious gaps
which occurred in trying to apply this theory to the observed facts by
placing