494 



BOTANICAL GAZETTE 



[DECEMBER 



definite relation between the length of the cortical cell and the 

 epidermal cell which decides whether the epidermal cell shall 

 become extended into an outgrowth or not. Fig. 3 shows a haired 

 cell longer than the adjoining cortical cell, and fig. 4 shows two 

 short epidermal cells adjoining one cortical cell. These measure- 

 ments are corroborated by observations made 

 throughout the work, many forms and all 

 possible variation in length of cortical and 

 epidermal cells being found. 



Position of nucleus. — The position of the 

 nucleus has been found to have no relation 

 whatever to the hair or to its initial forma- 

 tion. When the wall first swells, the entire 

 wall bulges; later there^'is a greater swelling 

 in one portion of it, the nucleus may not be 

 near that portion; if 

 the nucleus is near 

 that portion, it may 

 not follow the growth 

 of the hair and be 

 found near the tip of the hair, but remain 

 in the base of the hair or in another part 

 of the cell. There appears to be no rela- 

 tion between the position of the nucleus 

 and the formation of the hair. 



Fig. 3 Fig. 4 



Figs. 3, 4 — Fig. 3, 

 haired cell longer than 

 adjoining cortical cell; 

 fig. 4, two short epider- 

 mal cells adjoining one 

 cortical cell. 



IN AIR MEDIUM 



Fig. 5 



Figs. 5, 6.— Fig. 5, bulg- 

 ing of entire wall; fig. 6, 

 showing a narrowing of the 

 swollen portion. 



a) The physical character of walls 1,2, 

 4, 6. — The first evidence of the formation 

 of a root hair is the bulging of the entire 

 wall 1, as shown in fig. 5; then a portion 

 of the wall stretches more than the rest 

 and there is a narrowing of the swollen portion, as in fig. 6; but it 

 may be noted that the base of a root hair is always greater 

 in diameter than the rest of the hair, as in fig. 7. Seedlings of 

 endive and lettuce demonstrate this fact. Branching of the hairs 

 is common, indicating a difference in the physical character of the 



