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 a fantastic emphasis upon sexual selection. That is, much
progress was accounted for through the selection by the females of the
superior males. This, as a prime factor in evolution, has since been
almost "wholly discredited" (Kellogg's phrase) by the careful
experiments of Mayer, Soule, Douglass, Dürigen, Morgan and others. The
belief in sexual selection involved a long string of corollaries, of
which biology has about purged itself, but they hang on tenaciously in
sociological and popular literature. For instance, Ward believed in the
tendency of opposites to mate (tall men with short women, blonds with
brunettes, etc.), although Karl Pearson had published a statistical