takes a high polish. A fibre, resembling whale-bone, separates from the margins of old leaves.

Vegetable Ivory is the hard albumen of the seeds of Phytelebhas macrocarpa.

The Oil Palm (Elaïs guineensis) of West Africa affords Palmoil, used in the manufacture of soap and candles. The oil is obtained from the fruits. 885, 138 hundredweights of the oil were imported in 1877.

Sago is obtained from the farinaceous cellular tissue of the trunk of species of Sagus, growing in the East Indian Islands. Palm sugar is prepared from the juice of Phenix and Borassus

in India.

Rattan canes are the long flexible stems of Indian species of Calamus, which resemble cordage stretched among the trees of their native Indian forests.

SUB-CLASS, Petaloideæ.

64. Natural Order—Alismaceæ. The Alisma Family. DISTRIBUTION.-A small but cosmopolitan aquatic Order. British genera 6, species 9.

Perianth of 6 leaves. Pistil apocarpous. Ovary superior. Type-Water Plantain (Alisma Plantago).

FIG. 166.-Longi

tudinal section

of achene of F1. 165.-Vertical section of flower

same.

of Water Plaintain.

FIG. 167.-Embryo of same removed from the seed.

An erect aquatic perennial herb, with radical petiolate leaves, and unequal whorled peduncles forming a loose pyramidal panicle.

OBSERVE the difference between the submerged leaves reduced to linear petioles, and those which rise above the

:

water in Water Plantain the sepaloid outer and petaloid inner perianth-leaves of Alisma: the stamens in three series (9 altogether) in Flowering Rush (Butomus), and the anomalous placentation of the same species; the numerous ovules not being confined to the ventral sutures of the carpels, but scattered over the entire walls. Arrowhead Sagittaria) differs from Alisma in having the flowers unisexual and monoecious.

65. Natural Order- Hydrocharideæ. charis Family.

The Hydro

DISTRIBUTION.—Another small cosmopolitan aquatic Order.—British genera 3, species 3.

Floating or submerged Plants.

Flowers unisexual. Ovary

syncarpous, inferior.

Type-Common Frogbit (Hydrocharis Morsus-ranæ). Floating herb, with petiolate orbicular leaves, and dioecious pedicellate flowers.

OBSERVE the leaf-buds, about the size of small peas, formed by the plant in autumn. These develop separate plants in the following spring. Two or three buds thrown into a pond have speedily covered it with Frog-bit.

The "New Water-weed" (Elodea canadensis), an American plant, was first remarked in Britain in 1817, but was a rare plant prior to 1848, since about which time it has become distributed with marvellous rapidity in the rivers, canals and ponds of the midland counties.

As pistillate flowers only are found, no seeds can be perfected, so that the multiplication is solely by the breaking up of the plant into fragments, each fragment originating an independent plant.

A South European species (Vallisneria spiralis), with long narrow leaves, is commonly grown in fresh-water aquariums. The small pistillate flowers rise, upon a slender peduncle, to the surface of the water in which the plant grows, reaching a great length when the water is deep. The staminate flowers, on the other hand, are sessile near the root; and when their pollen is ripe, they break off from the plant and float to the surface, where they fertilize the stigmas. The leaves are well adapted for showing the "rotation" of the cell-sap under the microscope.

66. Natural Order-Liliaceæ. The Lily Family.

DISTRIBUTION.-A large Order, numerously represented in each quarter of the globe.-British genera 17, species 30.

Herbs (or a spinose shrub). Perianth-segments petaloid, stamens 6 (except Paris). Ovary superior.

FIG. 169.-Vertical section of flower of Wild Tulip. Type-Wild Tulip (Tulipa sylvestris).

A bulbous herb, with 1 to 3 narrow lanceolate leaves, and a single terminal large yellow flower upon an erect scape.

This Order is a very large one, including many species, which deviate more or less from the above Type. As Sub-types, represented in Britain, observe :

1. Butcher's Broom (Ruscus aculeatus), (the only British monocotyledonous shrub), bearing dioecious flowers upon flat spinose branches, which would be taken for leaves were they not axillary productions, springing from the axils of minute scales, which represent the true leaves. A young shoot is required to show the true scale-like leaves, as they wither very soon. Compare, with the leaves of Butcher's Broom, the scale-like leaves of Asparagus, bearing a fascicle of slender acicular branchlets (cladodia) in their axils. This plant grows wild upon some parts of the British

coast.

2. Herb Paris (Paris quadrifolia), anomalous amongst Monocotyledons from the tetramerous symmetry (parts in fours) of the flowers. The perianth is, normally, double, with 4 leaves in each whorl, 8 stamens, and 4 carpels. The parts of the perianth vary, however, from 3 to 6.

OBSERVE the structure of the bulb, exhibited in a crosssection of Hyacinth or Onion, and of White Lily; in the two former the scales are broadly overlapping (tunicate bulbs), in the last-named they scarcely overlap the bulbels in the axils of the leaves of Lilium bulbiferum, common in gardens; these are capable of independent O. B.

Q