Fig. 148.—Embryo of the common liver fluke (Fasciola hepatica), boring into a snail. × 370. (After Thomas, 1883, p. 285, Fig. 4.)
Fig. 149.—Sporocyst of the common liver fluke which has developed from the embryo, and contains germinal cells. × 200. (After Leuckart, 1889, p. 109, Fig. 67 B.)
Fig. 150.—Sporocyst of the common liver fluke, somewhat older than that of Fig. 149, in which the germinal cells are giving rise to rediæ. × 200. (After Leuckart, 1889, p. 109, Fig. 67 C.)
(c) Free-swimming ciliated miracidium (Fig. 148).—As already stated, this organism is entirely different from its mother. It measures about 0·15 mm. long; is somewhat broader in its anterior portion than in its posterior portion; on its anterior extremity we find a small eminence, known as a boring papilla; the exterior surface of the young worm is covered with numerous cilia, which by their motion propel the animal through the water; inside the body we find in the anterior portion a simple vestigial intestine and a double ganglionic mass provided with a peculiar pigmented double cup-shaped eye-spot; in the posterior portion of the body cavity are found a number of germ cells, which develop into individuals of the next generation.
Fig. 151.—Redia of the common liver fluke (Fasciola hepatica), containing germinal cells which are developing into cercariæ. × 150. (After Leuckart, 1889, p. 269, Fig. 129 A.)
Fig. 152.—Redia of the common liver fluke, with developed cercariæ. × 150. (After Leuckart, 1889, p. 270, Fig. 130.)