On Cell-wall Structure as seen in Cotton Hairs. 439 



" Ayrton spring." This change is apt to complicate observations on wall 

 structure. 



The Fuzz Hairs. 



In a previous communication,* one of us has pointed out that fuzz and lint 

 appear to be identical in all respects, except that growth in length is inhibited 

 in fuzz, while growth in wall thickness is restricted in the lint. None of the 

 present observations have revealed any further differences. In many cases 

 we have found it convenient to try out new methods, or hypotheses, on the 

 fuzz hairs before attempting to apply them to the more delicate lint. 



Conclusions. 



1. A spiral fibrillar radial structure exists in every growth-ring of the cell- 

 wall of the cotton hair. 



2. The simple pits of the cell-wall are a special case of this general 

 structure. 



3. The pattern of the spiral appears to be predetermined during growth in 

 length. 



4. This pattern is preserved through all the growth-rings cf the secondary 

 wall thickening. 



5. The number of fibrils in cross section of one hair is of the order of 

 1,000 upwards. 



6. The pattern (direction, reversal, and pitch) of these spirals seems to be 

 the major determinant of the externally visible convolutions of the hair. 



7. There are indications that the unknown cellulose-aggregates, which 

 compose any one spiral fibril, have a definite geometric conformation, 

 suggestive of stereo-isomerism. 



8. Attempts to elucidate the cellulose-structure further, as by X-rays, will 

 probably have to take account of this spiral fibril arrangement. 



While assistance in various ways has been given by our colleagues in the 

 Experimental Department of the Fine Cotton Spinners' and Doublers' Associa- 

 tion, to whose Executive Directors we are indebted for permission to publish 

 this account, we would wish especially to acknowledge the interest and 

 assistance of Dr. Mary Cunningham. The influence of Dr. H. E. Williams in 

 re-energising this inquiry has already been acknowledged, while the inde- 

 pendent development of work along similar lines by Dr. S. C. Harland and 

 Mr. Denham, at the Shirley Institute, has been of indirect assistance. 



* W. L. B., "The Existence of Daily Growth Rings in the Cell-wall of Cotton Hairs," 

 loc. cit. 



