. Beginners zoology. Zoology. Fig. 76.—Two pairs OF NepHRIDIa in a worm (diagram). ridium has an inner open end within the body cavity, and its outer end opens by a pore on the surface between the setae. The nephridia absorb waste from the hquid in the celovi, or body cavity surrounding the food tube, and convey it to the outside. Respiration. — The skin of the earthworm is moist, and the blood capillaries approach so near to the surface of the body that the oxygen is constantly passing in from the air, and carbon dioxide passing out; hence it is constantly breathing through all parts of its s
. Beginners zoology. Zoology. Fig. 76.—Two pairs OF NepHRIDIa in a worm (diagram). ridium has an inner open end within the body cavity, and its outer end opens by a pore on the surface between the setae. The nephridia absorb waste from the hquid in the celovi, or body cavity surrounding the food tube, and convey it to the outside. Respiration. — The skin of the earthworm is moist, and the blood capillaries approach so near to the surface of the body that the oxygen is constantly passing in from the air, and carbon dioxide passing out; hence it is constantly breathing through all parts of its skin. It needs no lungs nor special respiratory organs of any kind. Reproduction.—When one individual animal produces both sperm cells and tgg cells, it is said to be hermaphrodite. This is true of the earthworm. The egg cell is always fertilized, however, not by the sperm cells of the same worm, but by sperm cells formed by another worm. The openings of these ova7-ies consist of two pairs of small pores found in most species on the ventral surface of the fourteenth segment (see Fig. 77). There are also two pairs of small receptacles for temporarily holding i\\e foreign sperin cells. One pair of the openings from these receptacles is found (with diffi- culty) in the wrinkle behind the ninth segment (Fig. 77), and the other pair behind the tenth segment. The sperm- aries are in front of the ovaries (Fig. 77), but the sperm ducts are longer than the oviducts, and open behind tlicm on the fiflft-nth segment (Figs. 77, 78). The worms exchange sperm cells, but not. Fig. 77. — Sperm (f/) and egg glands {es) of 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 Coleman, Walter M. Toronto : Macmillan
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectzoology, bookyear1921
