s which
are alternative to each other in Mendelian inheritance. Instead of a
single pair, there may be a group of "multiple allelomorphs," each
member being alternative to every other member of the group.

ALLELOMORPHISM, a relation between two or more factors, such
that two which are present in one zygote do not both enter into the same
gamete, but are separated into sister gametes.

BIOMETRY (life measure), the study of biology by statistical
methods.

BRACHYDACTYLY (short-finger), a condition in which the bones,
particularly of the fingers and toes, fail to grow to their normal
length. In well-marked cases one of these is a reduction from three
phalanges or joints to two.

CHARACTER (a contraction of "characteristic"), a term which is
used, often rather vaguely, to designate any function, feature, or organ
of the body or mind.

CHROMOSOME (color body, so called from its affinity for certain
stains), a body of peculiar protoplasm, in the nucleus of the cell. Each
species has its own characteristic number; the cells of the human body
contain 24 chromosomes each.

CONGENITAL (with birth), present at birth. The term fails to
distinguish between traits which are actually inherited, and
modifications acquired during prenatal life. In the interest of clear
thinking its use should be avoided so far as possible.

CORRELATION (together relation), a relation between two
variables in a certain population, such that for every variation of one,
there is a corresponding variation of the other. Mathematically, two
correlated variables are thus mutually dependent. But a correlation is
merely a statistical description of a particular case, and in some other
population the same two variables might be correlated in a different
way, other influences being at work on them.

CYTOLOGY (cell word), the study of the cell, the constituent
unit of organisms.

DETERMINER (completely end), an element or condition in a
germ-cell, supposed to be essential to the development of a particular
quality, feature, or manner of reaction of the organism which arises
from that germ-cell. The word is gradually falling into disuse, and
"factor" taking its place.

DOMINANCE (mastery), in Mendelian hybrids the capacity of a
character which is derived from only one of two generating gametes to
develop to an extent nearly or quite equal to that exhibited by an
individual which has derived the same character from both of the
generating gametes. In th