49 6 



BOTANICAL GAZETTE 



IDECEMBER 



Figs. 13, 14. — Fig. 13, root hair mounted 

 in 0.24M sucrose; fig. 14, root hair after 

 being placed in 0.40M sucrose. 



out if it happens to be at the tip of the root hair, but in case it is 

 in or near the base of the cell it remains within the root hair. 

 The break in the wall is immediately closed as the membrane 

 springs back, and it is hard to detect the point of rupture except 

 for the position of the escaped protoplasmic contents. The 



younger cells are more likely to 

 burst than are the older ones. 

 Fig. 13 (a) shows a radish root 

 hair mounted in o . 24M sucrose 

 solution; fig. 14 (b) is the same 

 cell after being put in a o . 40M 

 sucrose solution. It is to be 

 noted that the walls corre- 

 sponding to 2, 4, 6 are only 

 very slightly changed, and 

 wall 1 has decreased, thus showing that even in the same cell the 

 physical condition of wall 1 is unlike that of walls 2, 3, 6. In cells 

 which do not burst when mounted in water, the surface of wall / is 

 increased, as evidenced by a 

 swollen tip which may or may 

 not assume odd shapes. This 

 indicates that wall 1 of these 

 plants has a greater resistance, 

 thereby indicating a variation 

 in the epidermal cells of differ- 

 ent plants, as well as a differ- 

 ence in wall / from walls 2, 4, 6. 

 It is frequently seen in many 

 forms, for example, alfalfa, cab- 

 bage, and Verbascum, that short 

 root hairs are mingled with long 



ones, giving the appearance of younger and older ones being 

 together (fig. 15). The difference may be one of time of formation 

 or of a variability in the growth of wall 1; at least in these forms 

 the length of the hairs is not a grading one as seen in the forms 

 usually figured. 



Short root hairs mingled with 



