Bulletin Volume 221-222

Bulletin Volume 221-222

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 edition. Excerpt: ...to the brachiopod Chonetes sarcinulatus. From Stadtfeld. Fig. 37. The tube Hicetes overgrown by polyp-cells of different series. Fig. 38. An etching of the coral showing an actual attachment of the worm tube to the snail-shell Loxonema. Fig. 39. Vertical section of a coral showing the worm tube entrenched between the polyp-cells. Fig. 40. An almost unique illustration of the attachment of the American Pleurodictyum to the brachiopod Chonetes eoronatus. ent coral. In many cases, such as that illustrated in figure 38, the worm tube is directly fixed to the gastropod; again it may be free of the gastropod and separated from it by the thickened basal covering or epitheca of the coral. With the multiplication of cell growth and the upward trend of the coral, the worm began its convoluted growth, its tube growing as much at one end as at the other and with the same curvature at each end. Many of the existing tubicolous as well as the boring worms have their tubes open at both ends. In view of the regularity of coiling shown in some of the commensal worm tubes it is interesting to notice that in this case the worm, after making a start, gets its double coil into parallelism for from one-half to an entire turn and then each arm starts off into a direct course outward and upward following the radial path of the coral cells. These tubes often pass in and out between the cells, shut off from them by secretions of the coral substance, keeping their extremities always at the tentacular surface, and very seldom is there evidence of the worm encroaching on the polypite cells. Still this may occur and the worm tube occasionally becomes encased by a young polypite and holds a position in the center of the cell. Not always does the growth of coral and...
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Product details

  • Paperback | 28 pages
  • 189 x 246 x 2mm | 68g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236962567
  • 9781236962560