The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . rolledand protruded from theopened shell; in this casethe tentacles alsoFig. diagram of the left half straighten themselves andof an Argiope {Megathyris), which has wave about m the water,been bisected in the median plane. The Body Cavity.—The 1. The ventral valve. various internal organs of 2. The dorsal valve. the brachiopod body, the 3. The pedicle. alimentary canal and liver, 4. The mouth. the excretory organs, the 5. Lip which overhangs the mouth heart, numerous muscles and runs all roun
The encyclopdia britannica; a dictionary of arts, sciences, literature and general information . rolledand protruded from theopened shell; in this casethe tentacles alsoFig. diagram of the left half straighten themselves andof an Argiope {Megathyris), which has wave about m the water,been bisected in the median plane. The Body Cavity.—The 1. The ventral valve. various internal organs of 2. The dorsal valve. the brachiopod body, the 3. The pedicle. alimentary canal and liver, 4. The mouth. the excretory organs, the 5. Lip which overhangs the mouth heart, numerous muscles and runs all round thelophophore. and the reproductive 6. Tentacles. organs, are enclosed in a 7. Ovary in dorsal valve. cavity called the bodyLiver diverticula. cavity, and since this cavityOcclusor muscle—its double origin (i.) is derived from the is shown. archicoel and is from the Internalopeningof left nephridium. first surrounded by mero-External opening of the same. < ? -^• !„i— Ventral nerve ganglion 15. The heart. 16. Dorsal adjustor 9- blast, (ii.) communicateswith the exterior throughthe nephridia or excretoryorgans, and (iii.) gives riseby the proliferation of thecells which line it to theova and spermatoza, it is ofthe nature of a true coelom. The coelom then is a spacious chambersurrounding the alimentary canal, and is continued dorsally and ven-trally into the sinuses of the mantle (fig. 21). Some of the endothelialcells lining the coelom are ciliated, the cilia keeping the corpusculatedfluid contents in movement. Others of the endothelial cells show agreat tendency to form muscle fibres. Besides this main coelomiccavity there are certain other spaces which F. Blochmann regardsas coelomic, but it must be remembered that his interpretation rests largely on histological grounds, and at present embryological con-firmation is wanting. These spaces are as follows:—(i.) the greatarm-sinus; (ii.) the small
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectencyclo, bookyear1910
