Page:The Oak.djvu/43

 root would show a more or less loose sheath of cells in addition to and outside this piliferous layer. This is the root-cap, which is a thimble-shaped sheath of looser cells covering the tip of the root as a thimble covers the



5.—A. Transverse section of young root under a lens, showing the axis cylinder, a; epidermis or piliferous layer, e; and the cortex between. B. The same, more highly magnified: c, cortex; p, phloëm ; x, xylem; C. A portion still more highly magnified: ph, phloëm; p, pith; per, pericycle; sh, sheath (endodermis); other letters as before.

end of the finger, only we must imagine the extreme tip of the finger organically connected with the inside of the cap to make the analogy suitable (see Fig. 6). The