A small-angle peak has been found by X-ray scattering measurements on the dry dragline silk of Nephila clavipes. The weak peak, located on the equatorial axis, yields a long period of approximately 45 Angstrom. Probably it corresponds to the lateral spacing of the crystals and is determined kinetically during the formation of the nanofibers. (C) 2000 Elsevier Science Ltd. All rights reserved.