Hemlock. Fig. 4.—Small portion of cross-section of bark

Fig. 4.—Small portion of cross-section of bark of Tsuga Mertensiana, magnified about 50 diameters.
c, c, c, bands of secondary cork;
a, intervening dead tissues composed of sieve and parenchymatous elements, and like the other species, rich in tannic, resinous and coloring matters;
s, s, groups of stone cells;
m, m, relatively large, fusiform medullary-ray cells;
b, band of large parenchymatous cells;
cr, crystal cell;
ca, cambium cells.

This image is from Structure of our Hemlock Barks in the July issue of the American Journal of Pharmacy, 1895.