The biological nature of reproduction in animals begins with a description of fission is one-called creatures and the budding process in hydra. Sexual reproduction applies to two groups of animals,- those who mate by chance and those who mate by choice. The habits of salmon and birds are prime examples from each group. How reproduction differs in mammals and in what manner the fetus grows in humans as well as its importance as a gene carrier carries the story up the scale of the animal kingdom. Clear, informative writing makes this a good supplement to readings in biology as well as an introduction prior to a formal course.