. Animal biology. Zoology; Biology. SPONGES 131 153. Canal Systems.—In sponges there are three principal types of canal systems, known as the ascon, sycon, and rhagon types (Fig. 54), of which the ascon is the simplest. The body of a sponge of this type has a thin wall which is penetrated by simple canals that run clear through to the gastral cavity. In this type flagellated cells line this Fig. 53.—Different types of sponges. A, Grantia ciliata (Fabricius), one of the Cal- carea, a simple sponge showing colony formation and budding. X 2. B, skeleton of Eupledella sp., a hexactinellid
. Animal biology. Zoology; Biology. SPONGES 131 153. Canal Systems.—In sponges there are three principal types of canal systems, known as the ascon, sycon, and rhagon types (Fig. 54), of which the ascon is the simplest. The body of a sponge of this type has a thin wall which is penetrated by simple canals that run clear through to the gastral cavity. In this type flagellated cells line this Fig. 53.—Different types of sponges. A, Grantia ciliata (Fabricius), one of the Cal- carea, a simple sponge showing colony formation and budding. X 2. B, skeleton of Eupledella sp., a hexactinellid sponge known as Venus' flower-basket, showing the form and general structure; the spicules are white and like spun glass. X }4. C, Chalina oculata Pallas, one of the marine Demospongiae. {From Minchin, in Lankester's "A Treatise on Zoology," by the courtesy of A. and C. Black.) X H- D, Ephydatia fluviatilis (Linnaeus), a fresh-water sponge belonging to Demospongiae. {From Zacharias, ''Die Tier- undPflanz- enwelt des ;) X %. In the sycon type a more complex plan is presented, with incurrent and radial canals. The ostia lead into incurrent canals which do not open into the gastral cavity; radial canals open into the gastral cavity but not to the outside. The two types of canals lie side by side and are connected by minute pores. The radial canals are lined with the flagel- lated 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 Wolcott, Robert Henry, 1868-1934; University of Nebraska (Lincoln campus). Dept. of Zoology. New York ; London : McGraw-Hill Book Company, Inc.
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