. Outlines of zoology. Zoology. ASTEROIDEA. 229 From the dorsal surface and sides of a star-fish in a pool, numerous transparent processes may be seen hanging out into the water. They are the simplest possible respiratory structures, contractile outgrowths of the skin with cavities continuous with the ccelom, and are called "; It is likely that pigmented cells of the body cavity fluid act like rudimentary red blood corpuscles ; the water vascular system may help in aeration; and the whole body is, of course, continually washed with i~M- Fig. 100. â -Diagrammatic cr
. Outlines of zoology. Zoology. ASTEROIDEA. 229 From the dorsal surface and sides of a star-fish in a pool, numerous transparent processes may be seen hanging out into the water. They are the simplest possible respiratory structures, contractile outgrowths of the skin with cavities continuous with the ccelom, and are called "; It is likely that pigmented cells of the body cavity fluid act like rudimentary red blood corpuscles ; the water vascular system may help in aeration; and the whole body is, of course, continually washed with i~M- Fig. 100. â -Diagrammatic cross section of star-fish arm.' After Ludwig. Radial nerve ; , radial blood vessel according to Ludwig, septum in blood vessel according to others ; , radial water- vessel ; , ampulla ; t/., tube-foot; , a pyloric caecum cut across; , a calcareous spine ; £-., a skin-gill; lac., spaces in the skin ; go., ova in ovary ; , ambulacra! ossicle. The " skin-gills " are said to have an excretory function ; for phagocytes, bearing waste, seem to traverse their walls. It may also be that excretion is somehow concerned in forming the carbonate of lime skeleton, but facts are wanting. The sexes are separate, and they are like one another, both externally and internally. The organs develop period- ically, and lie in pairs in each arm. Each is branched like an elongated bunch of grapes, and is surrounded by a blood sinus. Each has a separate duct, which opens on a porous. 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 Thomson, J. Arthur (John Arthur), 1861-1933. Edinburgh, Glasgow and London, H. Frowde and Hodder & Stoughton
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Keywords: ., bookauthorth, bookcentury1800, bookdecade1890, booksubjectzoology
