554 



Dr. W. L, Balls. The Existence of Daily 



in, the number of layers increases day by day up to a maximum of 25, when 

 thickening is complete. 



As growth is arrested by sunshine in the middle of each day in Egypt, the^ 

 number of these layers corresponded to the number of nights during which 

 the growth in thickness of the cell-wall had continued. 



These concentric layers in the wall of Egyptian cottonyhairs are thug rings- 

 of nightly growth, differentiated by heterogeneity like the annual rings in 

 timber. 



These rings are coarser, more sharply demarcated, and less regular, in fuzz- 

 hairs than in lint-hairs. The later rings in fuzz-hairs may resemble those of 

 lint-hairs. 



Certain abnormal appearances indicate that the cellulose wall may grow 

 for a time without being in full contact with the ectoplasm. 



I have to acknowledge much valuable assistance in our laboratory from 

 Dr. Mary Cunningham in the adjustment, application and interpretation of 

 the chemical treatment, and from Mr. C. E. Cross, F.E.S., in directing my 

 attention to the chemical problems of cotton. 



My thanks are also due to the Fine Cotton Spinners' and Doublers' 

 Association, Ltd., of Manchester, for permission to publish this note, and for 

 having made possible the continuation, extension and application of my 

 previous researches. 



