546 



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



of five to tenfold, and with this amount there would seem to be no serious 

 destruction of the cellulose structure. 



o- /oo rn. m- 



FiQ. 9. 



Pigs. 8 and 9. — Complete fuzz-hair swollen by treatment, and details of growth-rings 

 in marked area at its tip. The two outermost rings broken away over actual tip. 

 The isolated portion of the 10th ring could not be seen to be in connection with 

 the main bulk of the ring. 



Observations. 



Intelligent understanding of organic structure must depend on knowledge 

 of its growth-history, and it will therefore be more convenient to treat the 

 observations from this point of view. 



The differentiation of epidermal cells on the testa of the cotton-seed to 

 form lint-hairs up to a length of 1 or 2 mm. was described by the writer, in 

 1905.* Certain manipulative difficulties intervened to prevent further 

 * " The Sexuality of Cotton," ' Khedivial Agric. Soc. Year Book,' 1905. 



