. American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits . theline A the point 4 was reached and another radius there fastened. Thuson from 4 to 5, from 5 to 6, and so aroinid the entire circle. The mechan-ical advantage of this order is apparent. Several times the central tenuiniof the radii were strengthened by lapping threads across them. This tendency to alternate apposition I liave frequently observed invarious species, and its character will be better shown by giving several other schemes
. American spiders and their spinningwork. A natural history of the orbweaving spiders of the United States, with special regard to their industry and habits . theline A the point 4 was reached and another radius there fastened. Thuson from 4 to 5, from 5 to 6, and so aroinid the entire circle. The mechan-ical advantage of this order is apparent. Several times the central tenuiniof the radii were strengthened by lapping threads across them. This tendency to alternate apposition I liave frequently observed invarious species, and its character will be better shown by giving several other schemes of the order .of progression in spinning radii. TheOrder of gpijgj-j-^gg ^Jq ^q^ present a complete sequence of the radii fiom the very beginning, but number from the point at which I haj)-pened to catch the spider at work. They are to be read as in Fig. 72, theorder of numerals showing the relative position of the radial lines in theorder of their spinning. The series will show, I think, that while no abso-lute mathematical regularity marks the succession, some method of alternu-titju eviilently dominates the spiders movements. She knows the necessity. 74. Order of insertingnine radii. Fii:. 75. Orderof six radii. Orderoffive radii. Flii. 73. Theorder of spinningin twelve radii. Epeira ver-tebrata. which exists for balancing such a peculiar and delicate structure, andadopts her mode of spinning to tlie exigencies of her spinningwork. Blackwall states that after the completion of the radii the spider pro-ceeds to the centre, turns around and pulls each radius with her feet toascertain its strength, breaking such as are defective, and replacing themby others. I have never seen anything of the kind; the spider in settlingherself and gathering the radial lines into her eight claws naturally jerksthem somewhat. But no sucli purpose was ever suggested to my mind asthat declared by Blackwall. He also says that the radii are composed ofdouble lines, a statement which my obse
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