. A manual of zoology. Zoology. 98 GENERAL TRIXCirLES OE ZOOLOGY water constantly through them (tig. 02); in the swimming ^\â orms, on the back; in the tube-dwelling worms, at the anterior end, jirojecting out of the tube (tig. 0 0 ; in most amphibians (tig. 4), on each side of the neck. More rareh' the digesti\e tract functions for water-breatliing; in tjie lishes, Enteropneusta, and tunicates gills have been formed in connection with the pharynx, its lateral walls being pierced by the gill-slits, which open to the on the surface of the body. The water containing oxygen in solution
. A manual of zoology. Zoology. 98 GENERAL TRIXCirLES OE ZOOLOGY water constantly through them (tig. 02); in the swimming ^\â orms, on the back; in the tube-dwelling worms, at the anterior end, jirojecting out of the tube (tig. 0 0 ; in most amphibians (tig. 4), on each side of the neck. More rareh' the digesti\e tract functions for water-breatliing; in tjie lishes, Enteropneusta, and tunicates gills have been formed in connection with the pharynx, its lateral walls being pierced by the gill-slits, which open to the on the surface of the body. The water containing oxygen in solution passes out through tlie gill-slits, and bathes the gill-lea\-es which. Fig. 63.âAnterior end of TcrchcUa ndnilosa (after Jlilne EdwardsV ph. pharynx; vd, dorsal, vv, ventral, blood-vessel; hr, gills; ', tentacles. arc richly provided with blood-vessels. The hind-gut also in many lishes, insects, and worms may become an accessory respiratory organ, being ftUed from time to time with fresh water. Aerial Respiration.âIn the air-breathing animals the respiratory apparatus is derived either from the digestive canal or from the skin. With the vertebrates the former is the case, since the lungs, either ilirecllv or by way of the trachea and bronchi, are in connection with the lumen of the digestive tract. On the contrary, in snails and spiders when the term 'lung' is used, it refers always to an invagination or sac of the skin; the trachea? of insects are similar tubes containing air, beginning at the surface of the body with a hole, the spiracle or stigma, and branching internally (fig. 60, si).. 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 Hertwig, Richard, 1850-1937; Kingsley, J. S. (John Sterling), 1854-1929, ed. and tr. New York, H. Holt
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1912
