GENERATION, the act of procreation or begetting, hence any one of the various methods by which plants, animals or sub stances are produced (Lat. generare). The subject may be divided into the following branches, viz.: (I) the first origin of life and Iiving beings, (2) non-sexual or agamic reproduction, and (3) gamic or sexual reproduction. For the first two of these branches see ABIOGENESIS, BIOGENESIS and PARTHENOGENESIS ; for the third and more extensive division, including (I) the formation and fecundation of the ovum, and (2) the development of the embryo in different animals, see REPRODUCTION and EMBRYOLOGY.