The facts and theories of embryology that appear at present to be of particular significance for the medical student are presented in an interesting and dynamic form. The author has made important contributions to the history of development in the pig, and the story is complete in its general outlines. In addition, much may be said in favor of basing a textbook on the only mammalian species that is readily available for class study, especially when the laboratory work is made the major part of the course. Attention is called to the principal differences in development between man and the pig. This edition has few except verbal changes over the first, except that the excellent chapter on the vascular system has been somewhat expanded.