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As partial proof for the conclusions drawn in a previous paper (13), x-ray diagrams of natural fibers were compared with those of fibers synthesized from bacterial cellulose membranes. During the preparation of these "synthetic fibers," certain interesting observations regarding the plastic behavior of the crystallite suggested a further study of the type and degree relationship between deformation and orientation. It is the purpose of the present paper to describe briefly this extended investigation and especially to point out the significance of the results in that they appear to throw additional light on the question raised in the earlier paper (13), namely, what is the nature of the crystallite? Further information in this connection is not only of theoretical interest but also of practical importance, especially in the production of regenerated cellulose sheets and fibers.Aside from a study of the characteristics of cellulose fiber diagrams themselves-a critical review of which has been given elsewhere (14)-one of the useful methods of investigating the configuration of the crystallite is to observe with x-rays its plastic behavior. Unfortunately, owing to the existence of a complex, ever varying, cylindrical cell wall, harboring numerous non-cellulosic materials, it is extremely difficult t o draw definite conclusions when the method is applied to natural fibers. Although bacterial cellulose membranes have little macroscopic resemblance to natural fibers, they offer a unique opportunity for studying certain fundamental problems relating to the fine structure of natural cellulose for the following reasons : (1) they possess a well-formed, natural cellulose, crystalline structure; (2) they exist ~1 8 a uniform membrane in a highly swollen or gel condition; (3) plastic flow can be readily produced in the 1

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When sodium hydroxide of suitable concentration reacts with cellulose, swelling compounds (alkali cellulose or soda celluloses) are formed. These compounds may be detected through the use of x-ray diffraction analysis, since they give diffraction patterns which differ from that of the original cellulose. When the alkali is washed out and the sample dried, a mercerized or hydrate pattern is obtained. Most of the x-ray work on mercerization has been concerned with the formation of these alkali celluloses (2,7,8,14,15,19,20,21). For example, Hess and coworkers (8) have shown that at room temperature several soda celluloses are formed, depending upon the concentration of the alkali solution. Between concentrations of 12.5 and 19 per cent, sodium cellulose I is formed, while at higher concentrations (above 22 per cent) a second swelling compound, sodium cellulose II, is formed. More recently they have worked out the dependence of formation of the several soda celluloses on the temperature and on the concentration of the sodium hydroxide (19) and their work indicates the presence of at least five soda celluloses.

1 N RECENT years, many new types of rayon have leen introduced to the trade, each claiming to be an improvement or at least to have new properties which make the fiher better adapted for specific end uses. This paper is a general interpretation of how the rayon industry has improved the properties of rayon. This will be developed more from the physicalchemical point of view rather than from the engineering or fiber technologist's viewpoint. and I shall borrow freely from the literature and our own research without attempting to give due credit to the many people who have contributed to the concepts discussed.at WESTERN OREGON UNIVERSITY on