This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 Excerpt: ...that the lobe was completely constricted off. The statement was based on the study of preserved material which certainly supported this interpretation; but an examination of living eggs plainly shows that I was in error The nearly synchronous cleavage of all these cells gives us the 32-cell stage (Fig. 124). Every cell ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1897 Excerpt: ...that the lobe was completely constricted off. The statement was based on the study of preserved material which certainly supported this interpretation; but an examination of living eggs plainly shows that I was in error The nearly synchronous cleavage of all these cells gives us the 32-cell stage (Fig. 124). Every cell is located as in Amphitrite, and their relative size is the same with two exceptions: d1J receives the extra material bequeathed by the cell d, of the 8-cell stage, and the four apical cells are of about the same size, --in Amphitrite the two dorsal ones are the larger. Every one of the thirty-two cells divides obliquely to the left, but not synchronously. Already (Fig. 124) three of the cells have spindles, while the others are in the so-called resting stage. The familiar rosette is formed in the typical fashion, and most of the other divisions take place as indicated in the remaining figures by spindles or arrows (Figs. 124-130). On account of the regularity of the cleavage and its resemblance to that of Amphitrite, I thought it unnecessary to introduce more figures. The division of the primary trochoblasts, colored brown, may be seen in Figs. 125--128; the position of the secondary trochoblasts and of c211' and c"A in Fig. 132; the mesoderm cells, the above-mentioned rosette, and the primary cross-cells in Figs. 126-131. An actual 64-cell stage does not occur in Cluetopterus, owing to the precocious division of certain cells. Soon after the rosette cells are formed, they ingest the polar globules just as do the apical cells of Lepidonotus at an earlier period (Figs. 127, 131, 132, p. 266). I have carried the cell lineage little beyond what may be called the ideal 64-cell stage, but some of the next divisions are of great interest. The ...
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Add this copy of The Early Development of Marine Annelids to cart. $37.63, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Santa Clarita, CA, UNITED STATES, published 2019 by Wentworth Press.
