II.

FIG.
1.Cuticle, Buttercup leaf24. Do.  Pine cone
2. Do.  Iris25.Vitta, Caraway Seed
3. Do.  Ivy leaf26.Cork
4.Spiral vessel, Lily27.Hair, Flower of Garden Verbena
5. Do.  root, (rhizome) Water Lily 28. Do.  fruit of Plane
6.Ringed vessel, Rhubarb29. Do.  do.
7.Chaff, after burning30. Do.  do.
8.Bifid hair, Arabis31. Do.  Lobelia
9.Hair, Marvel of Peru32. Do.  Cabbage
10.End of hair, leaf of Hollyhock33. Do.  Dead-nettle flower
11.Hair, Sowthistle leaf34. Do.  Garden Verbena flower
12. Do.  Tobacco35.Fruit-hair, Dandelion
13. Do.  Southernwood36.Hair, Thistle leaf
14.Group of hairs, Hollyhock leaf37. Do.  Cactus
15.Hair, Yellow Snapdragon38. Do.  do.
16. Do.  Moneywort39. Do.  Virginian Spider-wort
17.Hair, Geum40. Do.  Lavender
18. Do.  Flower of Heartsease41.Section, Lavender leaf, Hairs
19. Do.  Dockleaf   and perfume-gland
20. Do.  Throat of Pansy42.Section, Orange Peel
21. Do.  Dead-nettle Flower43.Sting of Nettle
22. Do.  Groundsel44.Hair, Marigold flower
23.Cell, Beech-nut45. Do.  Ivy

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.