In this paper absolute sterility is held to mean the condition of a woman who, under ordinary favourable circumstances for breeding, produces no living or dead child, nor any kind of abortion. Sterility is held to mean the condition of a woman who, under ordinary favourable circumstances for breeding, produces no living and viable child, or adds not one to the population. Relative sterility is held to mean the condition of a woman who, while she may or may not be absolutely sterile, while she may or may not be sterile, is, under ordinary favourable conditions for breeding, sterile in relation to the circumstance of time, or, in other words, in relation to her age and the duration of her married life.