Fig. 
. 17. 
18. 
19. 
20. 
21. 
99 
2 
yr 
zd. 
28. 
29 
32. 
AND HISTOLOGY OF PIPER BETLE. 383 
Hydathode with adjoining epidermal cells (early stage); side view. x 1100. 
Hydathode (more advanced than 17). x 1100. 
Hydathode (side view), fully formed. The figure is inverted, and the body-cell is 
omitted. x 1100. 
Hydathode with the stalk-cell having a spout. x 1100. 
Plan of the stalk-cell of a hydathode. The outer pentagon is the base, the next 
circle is the apex, and the inner two circles form the neck of the cell. х 1100. 
. Transverse section of the lamina, where the palisade-tissue is doubled for a short 
distance ; it shows three secretory cells. x 330. 
. Isolated hairs from the stem. х 330. 
24. 
25. 
26. 
Stoma from the stem, х 330. 
A three-rayed tracheid at a junction of veins in the lamina, x 330. 
A silicified (?) thickening in the upper hypoderma; see p. 366. х 330. 
Vascular bundle from the medullary region of the stem. x 70. 
Vascular bundle from the peripheral ring of the stem. x 70. 
. A cortical concentric bundle with peripheral xylem. х 330. 
30. 
ol. 
Transverse section of a mucilage-canal from the stem. х 3380. 
Collenchyma in the stem, showing formation of sclerenchymatous fibres within it 
(transverse section). x 980. 
Endodermis in the root with a transfusion-cell (transverse section). x 330. 
PLATE 19. 
. Transverse section of a fluted petiole from the basal region just above the insertion 
of the stipules. х 50. 
. Transverse section of a branch near the apex. Тһе oval piece lying outside is the 
terminal inflorescence of а sympodial system. The outer crescentic piece is a 
petiole cut across in the region of the stipules. The small intercalated bundles 
are to be seen between the larger ones, The middle crescentic piece is a sheath 
cut across. The inner crescentic piece is the next leaf. The central circular piece 
is the lateral axis arising from the axil of the outer leaf. x 40. 
5. Transverse section of an undeveloped lamina. The figure is inverted. The hypo- 
derma beneath the upper epidermis is double over only a portion of the section. 
The secretory cells are very conspicuous. The hydathodes can be seen along 
either border. x 166. 
3. Transverse section of the stem (advanced stage), the stray spots are secretory 
cells. х 30. 
. Transverse section of an underground root. х 30. 
