Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 an affinity to the Tunicnta by the mode of respiration. This in- teresting worm was discovered by Delle Chiaje, and its organization and development have been recently investigated by Al. Agassiz and Kowalevski [more recently by Bateson, Q. J. Mic. 8ci. 1884] (fig. 241). The most inte- resting point about this form is the structure of its larva, which renders its relationship to the Echinodermata probable. The larva was described by J. Miiller as Tornaria, and was regarded by him as an E
Elementary text-book of zoology (1884) Elementary text-book of zoology elementarytextbo0101clau Year: 1884 an affinity to the Tunicnta by the mode of respiration. This in- teresting worm was discovered by Delle Chiaje, and its organization and development have been recently investigated by Al. Agassiz and Kowalevski [more recently by Bateson, Q. J. Mic. 8ci. 1884] (fig. 241). The most inte- resting point about this form is the structure of its larva, which renders its relationship to the Echinodermata probable. The larva was described by J. Miiller as Tornaria, and was regarded by him as an Echi- noderm larva. It FIG. 241.—Young Ealunoglosmts, strongly magnified. Pr, Pro- (Joes, in fact, possess boscis, the numerous branchial slits are visible. . , . . , r a double band or cilia, like Bipinnaria. Of these two rows of cilia, one, the praeoral, forms a ring round the prse-oral lobe, while the other is larger and runs in a more longitudinal direction so as almost to join the former near the apical pole. There is also a transverse piw-anal ring of cilia (fig. 242, a, b). Internally a diverti- culum of the ar- chenteron gives rise to an independent sac forming the water-vascular sys- tem, while two from the side ; 1. from the dorsal surface. O, mouth; A, Palrs °f dlvei'tlCllla anus; S, apex, W, rudiment of water vascular system ; C, furnish the first heart; P, P', peritoneal sacs. rudiments of the body cavity. A pulsating heart is developed from a thickening of 'The History of Balanoglossus and Tornaria.' Memoirs of tJtc Aincricmi, Ar«t/r»/// of Arts and , Vol. 1873. E. Metschuikoif. Zritsclir. f. wisscnstfi. Tom 1870. 0 a -/i 7, ^^-^ P' FIG. 2l2,n, l. — Tnrmirin larva (after E. Metschnikoff). u, Seen
Size: 1147px × 1744px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
