The Shipley Collection of Scientific Papers Volume 70

The Shipley Collection of Scientific Papers Volume 70

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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. 1902 edition. Excerpt: ...and of the effect of different agents on the rate, would, I believe, be very interesting, and might lead to valuable results. I hope to be able to make such a study at some future time. Lehnert (loc. cit., p. 17) gives a table of the rate of movement (presumably in the case of the fresh-water forms the rate of the gliding movement) of several species of flat-worms. He gives no account of how the data were collected, but his values may be inserted here for the sake of comparison. His rates for Bipalium kewense and B. kewense viridis are--Usual rate, 1 to 1'33 mm. per second; occasional rate, 183 mm. per second. This agrees very closely with the rate for P. maculata given above (134). His rates for Geodesinus bilineatus and Dendroccehun lacteum are considerably slower (0 5--O GG mm. per second and 0"75--133 mm. per second respectively). Polycelis tenuis (166--183 mm. per second), Planaria polychroa (210--25 mm. per second, exceptionally 8'33 mm. per second), and Mesostomum tetragonum (2'CG mm. per second) show a markedly faster rate than the forms I have studied. Regarding the effect of different agencies on the rate of the gliding movement no special study lias been made, and I can only report a few incidental observations. Such a study should be made by exact quantitative methods, and this I have not had the opportunity to do. What the effect of light on the rate is, it seems to me, impossible to say with entire certainty. Cole and myself1 have found that light of great intensity (that obtained from a projection lantern with an electric arc as its source of illumination) causes a definite increase in the rate of gliding, but this increase has not been measured. The results of Parker and Burnett do not help us to answer this more

Product details

  • Paperback | 196 pages
  • 188.98 x 246.13 x 10.67mm | 362.87g
  • United States
  • English
  • black & white illustrations
  • 1236831829
  • 9781236831828