. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. e Fig. 5. — Diagrams comparing the early divisions of the posterior cell of the fourth quartet {d* or I\r) in Crepidula (a), Nereis (b), Clymenella (c), Uiiio {d), and Aricia {e). The numerals show the order of division. Cells destined to form entoblast (their fate as actu- ally observed in Crepidula and Nereis, but only inferred in the other cases) ruled in parallel lines, mesoblast dotted. After the divisions here shown, the symmetrical mesoblast- bands are formed from the dotted cells. workers
. Biological lectures delivered at the Marine Biological Laboratory of Wood's Holl [sic]. Biology. e Fig. 5. — Diagrams comparing the early divisions of the posterior cell of the fourth quartet {d* or I\r) in Crepidula (a), Nereis (b), Clymenella (c), Uiiio {d), and Aricia {e). The numerals show the order of division. Cells destined to form entoblast (their fate as actu- ally observed in Crepidula and Nereis, but only inferred in the other cases) ruled in parallel lines, mesoblast dotted. After the divisions here shown, the symmetrical mesoblast- bands are formed from the dotted cells. workers from the time of Rabl (1876) have accepted his view, though only very recently has the full strength of the evidence been developed. In the first place, it was shown through the studies of Rabl, Blochmann, and later workers, that while the posterior cell of the fourth quartet gives rise to the mesoblastic pole-cells the other cells are purely entoblastic. In the second place, the recent studies of Conklin and myself have shown that even the posterior cell of the fourth quartet {d') may contain entoblastic as well as mesoblastic material. I showed several. 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 Marine Biological Laboratory (Woods Hole, Mass. ). Boston, Ginn & Co
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectbiology
