Measurements of the reversing spiral in cotton hairs

Abstract

This paper resumes our study of the reversing spiral structure found in the cell wall of cotton hairs, and presents typical samples of the many thousands of measurements which we have made during the past three years in an attempt to interpret their significance by statistical methods. These measurements were made under the microscope by the use of elliptically polarized light, with eye-piece graticules and mechanical stage, the colour change being checked by direct observation of the structure whenever any doubt existed. It is not advisable to draw rigid conclusions as to the causation of the spiral reversals from the data here presented, because such conclusions would be pure inference, unsupported by direct observation. We have tried to grow cotton hairs in vitro , outside the boll, for such observation, but have failed so far. The data are therefore given as a record of facts, with no more speculation as to their meaning than is needed to make them cohere. We feel sure that their significance transcends the limits of the genus Gossypium , and that statistical study of the data, such as is beyond our competence, would give much information about the detailed mechanism of one part of the growth process.