The fundamental idea running through this paper is to correlate the crimps of textile fibers with bilateral structure which was found by the author and collaborators, and a series of results obtained by them on this line are reviewed. Section I outlines the study on the crimped rayon staple which gave rise to finding the bilateral structure. Several species of wool fibers are also endowed a priori with bilateral structure, which induces the fibers to crimp as shown in Section II. Section III deals with the mathematical analysis of the dynamics of crimp. The ideal form of crimp is the helical spring, which is preferred to the plane zig-zag from the practical point of view. Section IV describes the production of bilateral fibers made up of two components by the “conjugate melt spinning” process. It is important in the processes of treating the filaments and fabrics that the component polymers in each bilateral filament should be kept inseparable. The compatibility of the several pairs of polymers is estimated by the study of epitaxy, as mentioned in Section V. It is shown in Section VI that the chemical similarity between different polymers is also an essential factor to produce strong cohesion. In Section VII, some of the practical data of crimps, such as the diameter of helix and the number of crimps per unit length are shown with several kinds of conjugate-spun fibers as a function of degree of stretching before producing coiling, the conditions of heat treatment and so forth
