. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. FIG. 259.—Egg with embryo{a),and hatched larva (b) of Polystomum integerrimum ; Dk, operculum (after E. Zeller). to four weeks. It is easy then to observe the Polysto- mea in the process of reciprocal copulation. When the eggs are being laid, the parasite forces the the. 258-—Polystomum inte- gerrimum (after E. Zeller). 0, mouth; Go, genital opening; D, intestine ; IK, copulatory opening (lateral pads) ; Dg, yolk gland duct ; S, sucker ; Ov, ovary; If, hooks. anterior end of the body with o
. Elementary text-book of zoology, tr. and ed. by Adam Sedgwick, with the assistance of F. G. Heathcote. FIG. 259.—Egg with embryo{a),and hatched larva (b) of Polystomum integerrimum ; Dk, operculum (after E. Zeller). to four weeks. It is easy then to observe the Polysto- mea in the process of reciprocal copulation. When the eggs are being laid, the parasite forces the the. 258-—Polystomum inte- gerrimum (after E. Zeller). 0, mouth; Go, genital opening; D, intestine ; IK, copulatory opening (lateral pads) ; Dg, yolk gland duct ; S, sucker ; Ov, ovary; If, hooks. anterior end of the body with opening through the mouth of the bladder nearly as far as the anus. The development of the embryo takes place in water and occu- pies a period of many weeks, so that the young larvae are only hatched when the tad- poles have already acquired internal gills. Gyrodactylus, and possess four eyes, a pharynx and alimentary canal, as well as a posterior disc (for attachment), which is surrounded by sixteen hooks. They possess five transverse rows of cilia; three are ventral and anterior, two dorsal and posterior. There is also a ciliated cell upon the anterior extremity. The larvae now migrate The larvae resemble. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Claus, Carl, 1835-1899; Sedgwick, Adam, 1854-1913; Sinclair, F. G. (Frederick Granville), b. 1858. London, Swan Sonnenschein & co.
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Keywords: ., book, bookcentury1800, bookcollectionbiodiversity, bookdecade1890
