ABSORPTION OF WATER 



51 



47. Structure of Root-hairs. — The structure of root- 

 hairs, and their relation to the root as a whole, are illus- 

 trated in Figs. 40 and 41. It is seen at once, from the 

 figure, that they are epidermal cells, elongated at right 

 angles to the surface of the root, forming a thread-like 



Fig. 37. — Jack-in-the-pulpit {Arisama 

 Iriphyllum). Longitudinal section 

 through a root, rt, root-tip'; re, root- 

 cap. (After F. L. Pickett.) 



Fig. 38. — Roots of the water- 

 hyacinth {Eichornia crassipes 

 Solms), showing removable 

 root-caps; b, root-cap removed 

 from c. 



sac, closed at both ends. The typical cell-structure is 

 readily recognized — the cell-wall, the cytoplasm, closely 

 appressed to the inner surface of the wall, the vacuoles, 

 sometimes merged into one large vacuole occupying most 

 of the cell-space, and containing the cell-sap, and finally 

 the nucleus. 



