Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 METAMonrncsis. 2srj interstitial tissue filled with round cells is formed external to the lateral discs, and with participation of the thickening skin. This tissue becomes the seat of calcareous deposits, and forms the dermal skeleton of the adult Echinoderm (fig. 228 a, h). The canal of the dorsal pore has in the meantime changed its simple form and developed into the circular vessel with diverti- cula, which are destined to become the ambulacral trunks. As development prog
Elementary text-book of zoology, general part and special part: protozoa to insecta . elementarytextbo00clau Year: 1892 METAMonrncsis. 2srj interstitial tissue filled with round cells is formed external to the lateral discs, and with participation of the thickening skin. This tissue becomes the seat of calcareous deposits, and forms the dermal skeleton of the adult Echinoderm (fig. 228 a, h). The canal of the dorsal pore has in the meantime changed its simple form and developed into the circular vessel with diverti- cula, which are destined to become the ambulacral trunks. As development progresses, the young animal appears as a more or less spherical or pentagonal body, or as a star with short arms, in propor- f'iG. 22B.~B'pinnar'a frcm Trieste forminpr a stase in the develf pment of the Stir-Ssh (St) (after J. Muller). a. Earlier stage. M, stomach; A, anus; V, ambulacral rosette with ciliated tube opening by the dorsal pore, h, Older stage. tion as it predominates over the larva. Finally, after the sprouting out of the ambulacral feet, the young Echinoderm becomes separated from the larval body, which not unfrequently remains attached to the former, like the remnants of a broken-down framewoi'k. The stomrch, which is taken into the interior of the body of the Echinoderm, is torn from the oesophagus of the larva [Biinnnaria), and acquires a new oesophagus and mouth. The dorsal pore becomes the pore of the madreporic plate. The SynaiAvloi, on the contrary, are formed by the transformation of the entire body of the Aicricularia. Five tentacles appear in front
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