PLATE VI 





Fig. 1. Parallel bundle (0° spiral). 



Fig. 2. 9-5°. 





Br 



Fig. 3. 19-8°. 



Fig. 4. 40-7°. 



X-ray diagrams of spirals constructed using filaments of well-oriented artificial 



silk. Each spiral was less than 0-5 mm. diameter and therefore lay within the 



X-ray beam. The angles given are those between the filament and the spiral axis. 



Spiral axis parallel to long edge of page. 



[Facing p. 128 



