. Catalogue of the Chaetopoda in the British Museum (Natural History). Oligochaeta; Polychaeta. Fisj-. iO.—A. cristata. Statolith, and cuticular lining of statocyst. Fig. 41.—A. branclu'alif!. Stato- liths, and cuticular liinnj; of statocyst. and a cup-shaped mass, about 8 to 20 yu, in diameter, composed of reddish-brown pigment-spherules (PI. X, Fig. 25). In the early stage of larval life the eyes are actively functional, and during the first two days after hatching the larvae are phototropic; but by the third day this preference for light is lost. The eyes soon sink below the epidermis, and
. Catalogue of the Chaetopoda in the British Museum (Natural History). Oligochaeta; Polychaeta. Fisj-. iO.—A. cristata. Statolith, and cuticular lining of statocyst. Fig. 41.—A. branclu'alif!. Stato- liths, and cuticular liinnj; of statocyst. and a cup-shaped mass, about 8 to 20 yu, in diameter, composed of reddish-brown pigment-spherules (PI. X, Fig. 25). In the early stage of larval life the eyes are actively functional, and during the first two days after hatching the larvae are phototropic; but by the third day this preference for light is lost. The eyes soon sink below the epidermis, and become imbedded in the masses of ganglion-cells which form the dorsal and anterior portion of the brain. With the increase in the amount of pigment in the prostomial e])itlielium the eyes become difficult to find, and are finally indistinguishable. It seems unlikely that in adult specimens the eyes can have any functional importance.^ ' Arenicola is sensitive to light, resembling earthworms in its reaction to this stimulus, and, as in them, the response may be due to the stimulation of the sense-cells in the epidermis, especially of the anterior end; it is unlikely that it is due to specific action through the eyes, for the reasons given 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 Ashworth, James Hartley, 1874-1936; Ashworth, James Hartley. London, Printed by Order of the Trustees of the British Museum
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Keywords: ., bookcentury1900, bookdecade1910, bookpublisherlondo, bookyear1912
