FIG. 1. Cuticle, Buttercup leaf 2. Do. Iris 3. Do. Ivy leaf 4. Spiral vessel, Lily 5. Do. root, (rhizome) Water Lily 6. Ringed vessel, Rhubarb 7. Chaff, after burning 8. Bifid hair, Arabis 9. Hair, Marvel of Peru 10. End of hair, leaf of Hollyhock 11. Hair, Sowthistle leaf 12. Do. Tobacco 13. Do. Southernwood 14. Group of hairs, Hollyhock leaf 15. Hair, Yellow Snapdragon 16. Do. Moneywort 17. Hair, Geum 18. Do. Flower of Heartsease 19. Do. Dockleaf 20. Do. Throat of Pansy 21. Do. Dead-nettle Flower 22. Do. Groundsel 23. Cell, Beech-nut 24. Do. Pine cone 25. Vitta, Caraway Seed 26. Cork 27. Hair, Flower of Garden Verbena 28. Do. fruit of Plane 29. Do. do. 30. Do. do. 31. Do. Lobelia 32. Do. Cabbage 33. Do. Dead-nettle flower 34. Do. Garden Verbena flower 35. Fruit-hair, Dandelion 36. Hair, Thistle leaf 37. Do. Cactus 38. Do. do. 39. Do. Virginian Spider-wort 40. Do. Lavender 41. Section, Lavender leaf, Hairs and perfume-gland 42. Section, Orange Peel 43. Sting of Nettle 44. Hair, Marigold flower 45. Do. Ivy [Illustration: II.] * * * * * The hairs of plants form very interesting objects, and are instructive to the student, as they afford valuable indications of the mode in which plants grow. They are all appendages of and arise from the skin or epidermis; and although their simplest form is that of a projecting and elongated cell, the variety of shapes which are assumed by these organs is inexhaustible. On Plate II. are examples of some of the more striking forms, which will be briefly described. The simple hair is well shown in Figs. 18, 19, and 32, the first being from the flower of the heartsease, the second from a dock-leaf, and the third from a cabbage. In Fig. 18 the hair is seen to be but a single projecting cell, consisting only of a wall and the contents. In Fig. 19 the hair has become more decided in shape, having assumed a somewhat dome-like form; and in Fig. 32 it has become considerably elongated, and may at once be recognised as a true hair. In Fig. 8 is a curious example of a hair taken from the white Arabis, one of the cruciferous flowers, which is remarkable for the manner in which it divides into two branches, each spreading in opposite directions. Another example of a forked hair is seen in Fig. 13, but in this instance the hair is composed of a chain of cells, the three lower forming the stem of the hair, and the two upper being lengthened into the lateral branches. This hair is taken from the common southernwood. In most cases of long hairs, the peculiar elongation is formed by a chain of cells, varying greatly in length and development. Several examples of these hairs will be seen on the same Plate.