Growth-rings in the Cell Wall of Cotton Hairs. 547 



study of the developing fruit, and no method was found until 1913, when the 

 story was completely outlined* in connection with the physiological studies 



0-/00 m m 



Fig. 10. — As preceding, but showing portion near base. 



I i 



o. /oo rn.m. 



Fig. ] 1. — Adult lint-hair, showing swollen dimensions, and 23 rings as observed and 

 repeatedly counted. Original diameter of cell lumen practically unchanged, i.e., 

 approximately 010 mm. on major diameter, with wall-thickness of 0'004 mm., 

 making up a " ribbon- width " of O'OIS mm. 

 The wall-thickness of 004 mm. has been swollen to 0'030 mm. 



* 'Raw Cotton,^ pp. 80-85, etc. 



