segmentation of, [199];
polar bodies of, [218].
Molluscs, length of life of, [55];
determined by markings on shell, [14];
enemies of, [58].
Monoplastides, [115], [122], [125], [146], [159];
definition of, [120];
reproduction of, [149].
Mouse, length of life of, [6]; gestation of, [7].
Müller, F., on heredity of acquired characters, [320], [322].