A treatise on zoology . bres, amoebocytes and calcigenous cells,and intercellular, gelatinous, and fibrous substances. The muscle-fibre(Fig. XXIII. 6-9) derived from a single cell is smooth and straight, 28 ECHINODERMA—GENERAL DESCRIPTION clearly defined at the ends, with a lateral nucleus. A few striatedmuscle-fibres are known in Echinoidea (Geddes and Beddard, 1881 ;Hamann, 1887). A serai-muscular, hyaline tissue of wavy, nucleatedfibrils is peculiar to Crinoidea, and is called ligament are also muscles of endothelial origin. Connective tissuefibrils are nucleate and vary in len
A treatise on zoology . bres, amoebocytes and calcigenous cells,and intercellular, gelatinous, and fibrous substances. The muscle-fibre(Fig. XXIII. 6-9) derived from a single cell is smooth and straight, 28 ECHINODERMA—GENERAL DESCRIPTION clearly defined at the ends, with a lateral nucleus. A few striatedmuscle-fibres are known in Echinoidea (Geddes and Beddard, 1881 ;Hamann, 1887). A serai-muscular, hyaline tissue of wavy, nucleatedfibrils is peculiar to Crinoidea, and is called ligament are also muscles of endothelial origin. Connective tissuefibrils are nucleate and vary in length and shape; there are alsorounded or stellate cells (Fig. XXIII. 4, 2). Intercellular substance,secreted by mesenchyme cells, often attains great thickness inthe integument; it may remain a soft jelly, or become tough asindiarubber, or may split up into interlacing fibrils; it usuallycontains amoebocytes and ordinary connective tissue cells ; it formsalso interarticular substance (Fig. XXIII. 14), elastic ligament,. % occ^o^icOSS00 0Do oco-oO-c o^fPiPcO c ool^^ .VO0^0. eeO 0 0 0,«?,:e^o?oVeCcCO0v 2 3 6 Fio. XXIV. Stereom foriiiiition. 1, from the hinder portion of a Ilvteus of Echinus milktns. s, one oftlin siii)portiii;4 rods of tlie Plnteux; c, a t,linH-i)ronf:;pd spiciile surrounded by a , reart of tliecui) f)f lli)li,pvs (x fit)), G, portion of horizontal section of Holopns cup, showinj; relation ofirre^^ular (0 and re^ular (r) ster. oni (x 15). 1-3 (after Theel). 4 (after Secliger). 5, 0 (afterI. If. Carpenter). and the walls of internal organs. Parallel structures are found inthe
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
