Rilliet[112] cites cases tending to show that consanguineous marriages, in themselves pernicious, tend with certainty to lower vital force. The effects he divides into two categories; those which relate to the parents, under which head are:—
a. Failure of conception.
b. Retardation of conception.
c. Imperfect conception.
Those which relate to the progeny:—
a. Imperfections of various kinds.
b. Monstrosities.
c. Imperfect physical and mental organisation.
d. Tendency to diseases of the nervous system, such as epilepsy, imbecility, idiocy, deaf-mutism, paralysis, and various cerebral affections.
e. Tendency to strumous diseases.