ands.
Example, the beard.

SEX-LINKED, a term applied to traits which are connected with
sex _accidentally_ and not physiologically in development. The current
explanation is that such traits happen to be in the same chromosome as
the determiner of maleness or femaleness, as the case may be.
Color-blindness is the classical example in man.

SEXUAL SELECTION, the conscious or unconscious preference by
individuals of one sex, or by that sex as a whole, for individuals of
the other sex who possess some particular attribute or attributes in a
degree above or below the average of their sex. If the deviation of the
chosen character is in the same direction (plus or minus) as in the
chooser, the mating is called assortative; if in one direction
independent of the characteristic of the chooser, it is called
preferential.

SOMA (body), the body as distinguished from the germ-plasm.
From this point of view every individual consists of only two
parts,--germ-plasm and soma or somatoplasm.

TRAIT, a term used by geneticists as a synonym of "character."

UNIT-CHARACTER, in Mendelian heredity a character or
alternative difference of any kind, which is apparently not capable of
subdivision in heredity, but is inherited as a whole, and which is
capable of becoming associated in new combinations with other
characters. The term is now going out of use, as it makes for clearer
thinking about heredity to fix the attention on the factors of the
germ-cells instead of on the characters of the adult.

VARIATION, a deviation in the size, shape, or other feature of
a character or trait, from the mean or average of that character in the
species.

VESTIGIAL (footstep), a term applied to a character which at
some time in the evolutionary history of the species possessed
importance, or functioned fully, but which has now lost its importance
or its original use, so that it remains a mere souvenir of the past, in
a degenerated condition. Example, the muscles which move a man's ears.

ZYGOTE (yolk), the fertilized egg-cell; the united cell formed
by the union of the ovum and spermatozooen after fertilization.

ZYMOTIC, caused by a microoerganism,--a term applied to
diseases. Example, tuberculosis.

INDEX

A

Abderholden, E., 422

Acquired character, 437

Administrative aspects, 194

Adult mortality, 345

Afghans, 321

Africa, 290, 291

Agriculture, 307

Aguinaldo, E., 314

Aims of eugenics, 152