Two great processes are employed in the animal kingdom to assure the preservation of the species: either the parents do not concern themselves at all with their progeny, in which case the females give birth to an enormous number of young; or, on the other hand, they are full of solicitude for their offspring, cherishing and protecting them against the numerous dangers that menace them; and, in this last case, the young are few in number. Nature (since the expression is consecrated) proceeds sometimes by a lavish and lawless production, and sometimes by a sort of Malthusianism. Thus a cod lays every year about a million eggs, on which she bestows no care, and of which only the thousandth, or perhaps even the hundred thousandth part, escapes destruction; turtle-doves, on the contrary, only lay two eggs, but nearly all their young attain maturity. In short, the species is maintained sometimes by prodigality of births and sometimes by a great expenditure of care and affection on the part of the parents, especially of the female. It is almost superfluous to remark that analogous facts are observed in human natality, according as it is savage or civilised. With animals, as with men, sexual association, when it endures, becomes marriage, and results in the family, that is to say, a union of parents for the purpose of protecting their young. The care of the male for his progeny is more rare and tardy than that of the female. Among animals, as among men, the family is at first matriarchal, and it is only in the higher stages of the animal kingdom that the male becomes a truly constituent part of the family group; but even then, except among certain species of birds, his chief care is less to rear the young than to govern in order to protect them. He plays the _rôle_ of a despotic chief, guiding the family when it remains undivided after the rearing of the young, and most frequently acting like a polygamous sultan, without the purely human scruple in regard to incest. Just as we find amongst animals the two principal types of the human family, the matriarchate and the patriarchate, or rather the maternal and paternal family, so we may observe equally among them all the forms of sexual union from promiscuity up to monogamy; but for enlightenment on these interesting points of sociology, a rapid examination of the animal kingdom is worth far more than all generalities. II. _Marriage and the Rearing of Young amongst Animals._