The fine structure of phloem fibres II, Untreated and swollen jute

Abstract

Studies of the jute fibre by X-ray methods, under the polarizing microscope, and after swelling with various reagents, lead to the conclusion that the optical heterogeneity of the wall is not to be explained in terms of changes in cellulose chain direction. The evidence available shows that the wall is composed of chains forming a single, steep spiral. The wall spiral becomes steeper as the cell elongates and this continues until the onset of wall thickening. The fibre in many ways provides a study complementary to that of hemp. The outer layers of the wall are the least lignified and have the least resistance to swelling. The phenomenon of "ballooning" is therefore never observed, though structures resembling balloons may be produced by a special technique. For similar reasons transverse cracks are never observed during the swelling process. Impregnation with lignin seems to cause an increase in thickness of the wall even in the outer layers which are far removed from the cytoplasm-wall interface. The results fully confirm the conclusion already reached that observation of swollen material is usually entirely misleading.