n to it, though _ex hypothesi_ there is a tie of blood
between them. In England nothing short of an Act of Parliament can make
them akin; but in Scotland the subsequent marriage of the father with
the mother of the child changes the legal status of the latter and makes
it of kin with its father. These two examples make it abundantly evident
that kinship is with us a matter of law.

Among primitive peoples kinship occupies a similar position but with
important differences. As with us, it is a sociological fact; custom,
which has among them far more power than law among us, determines
whether a man is of kin to his mother and her relatives alone, or to his
father and father's relatives, or whether both sets of relatives are
alike of kin to him. In the latter case, where parental kinship
prevails, the limits of the kin are often determined by the facts of
consanguinity. In the two former cases, where kinship is reckoned
through males alone or through females alone, consanguinity has little
or nothing to do with kinship, as will be shown more in detail below.

Kinship is sociological, consanguinity physiological; in thus stating
the case we are concerned only with broad principles. In practice the
idea of consanguinity is modified in two ways and a sociological element
is introduced, which has gone far to obscure the difference between
these two systems of laying the foundations of human society. In the
first place, custom determines the limits within which consanguinity is
supposed to exist; or, in other words, at what point the descendants of
a given ancestor cease to be blood relations. In the second place
erroneous physiological ideas modify the ideas held as to actually
existing consanguine relations, as we conceive them. The latter
peculiarity does not affect the enquiry to any extent; it merely limits
the sphere within which consanguinity plays a part, side by side with
kinship, in moulding social institutions. If an Australian tribe, for
example, distinguishes the actual mother of a child from the other women
who go by the same kinship name, they may or may not develop on parallel
lines their ideas as to the relation of the child and his real father.
Some relation will almost certainly be found to exist between them; but
it by no means follows that it arises from any idea of consanguinity. In
other communities potestas and not consanguinity is held to determine
the relations of the husband of a woman to her offsprin