. A manual of zoology. I" PHYLUM PORIFERA 85 paragastric cavity, consists throughout of flagellate collared cells similar to those of the flagellate canals of Sycon. The majority of sponges, however, are more complicated in structure than Sycon. One of the causes of their complexity being that the canals, instead of being simple and straight, become branched, forming a system, often highly complicated, of ramifying channels. In these more complex sponges the flagellate collared cells are confined to 0 P,G. Ex Fig. 38.—Vertical section of a fresh-water sponge (Spongilla), showing the arran
. A manual of zoology. I" PHYLUM PORIFERA 85 paragastric cavity, consists throughout of flagellate collared cells similar to those of the flagellate canals of Sycon. The majority of sponges, however, are more complicated in structure than Sycon. One of the causes of their complexity being that the canals, instead of being simple and straight, become branched, forming a system, often highly complicated, of ramifying channels. In these more complex sponges the flagellate collared cells are confined to 0 P,G. Ex Fig. 38.—Vertical section of a fresh-water sponge (Spongilla), showing the arrange- ment of the canal-system. C, ciliated chambers; DP, dermal pores; Ex, exenrrent canals; GO, openings of the excurrent canals; PG, paragastric cavity; SD, subdermai cavities; O, osculum. (Modified from Leuckart and Nitsche's diagrams.) certain rounded dilatations of the canals — the flagellate chambers. Moreover, in the more complex forms the development of branches from the originally simple sponge, and the coalescence of neighbouring branches with one another, greatly obscure the essential nature of the sponge as a colony of zooids similar to the branches of Sycon; and this effect is increased by the development of a variety of infoldings of the ectoderm which appear in the higher 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 Parker, T. Jeffery (Thomas Jeffery), 1850-1897; Haswell, William A. (William Aitcheson), 1854-1925. New York, The Macmillan Company; London, Macmillan & Co. ,Ltd.
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishernewyo, bookyear1900
