fruit an achene enclosed by the free calyx-tube]; Strawberry [indefinite achenes upon a succulent rounded receptacle]; Blackberry and Raspberry [numerous drupels]; Meadow Sweet [several, about seven, follicles]; Rose [numerous free achenes enclosed in a concave succulent calyx-tube or receptacle]; and Apple [5 bony carpels adnate to the calyx-tube].

The Natural Order Rosacea furnishes our most valuable orchard trees, as well as many of our most beautiful garden flowers.

Species affording useful fruits are Apple, Pear (Pyrus); Quince (Cydonia); Medlar (Mespilus); Almond, Peach, Nectarine (Amygdalus); Cherry, Apricot, Plum (Prunus); Loquat (Eriobotrya); Strawberry (Fragaria); Raspberry and Blackberry (Rubus).

Some of the Order, as Almond, Peach, and the species of Prunus, contain prussic acid, the vapour of which, given off from a crushed leaf of Garden Laurel (P. laurocerasus) under an inverted tumbler, will soon destroy the life of an insect. Owing to the presence of this acid, the Oil of Bitter Almonds is a virulent poison.

From the petals of sweet-scented species of Rose the Attar or Otto of Rose is obtained. 100,000 Rose-flowers are said to be required to yield three drachms of the pure Attar.* It is consequently very costly, and is commonly adulterated with an Indian Grass Oil.

Mossy galls, called Rose Bedeguars or 'Robin Redbreast's Pincushions,' are frequent upon the Dog Rose (Rosa canina) in autumn, produced by the puncture of species of Cynips. If kept until the following spring, the young Cynips will be produced, also species of Ichneumon, which prey upon the Cynips.

The fruit-bearing species in cultivation afford a good opportunity of observing the different modes and effects of grafting. To secure the success of a graft it is essential that the cambium-layers of the graft and stock should be in contact, and the cut surface protected from evaporation. A section through an old graft shows, notwithstanding the complete union of the tissues of the graft

* From 28 to 40 lbs. of the petals in dry weather, or about alf the quantity when moist, yield 1 drachm of Attar.

and stock, that each retains the peculiar character of its own wood. This is particularly striking when the woods are of different colours or shades of colour, as when the Peach is grafted upon a Plum stock.

Bear in mind that the Garden Laurel, with large, shining leaves, and the Portugal Laurel, both very common garden shrubs, are species of Prunus, and have nothing to do with the true (Victor's) Laurel, belonging to the exotic Order Lauraceæ, a Family of Monochlamydeæ, with the anthers dehiscing by valves, like those of the Barberry.

23. Natural Order - Onagraceæ. Family.

The Enothera

DISTRIBUTION.-Temperate Zone of both hemispheres; less numerous between the Tropics.-British genera 4, species 13.

Herbs. Stamens 2, 4, or 8. Ovary inferior.

Type-Willow-herb (Epilobium hirsutum).

A tall perennial herb, with clasping lanceolate undivided leaves and rose-coloured regular flowers.

OBSERVE the dimerous symmetry of Enchanter's Nightshade (Circaa), the parts of the flower being in twos: the coloured calyx of Fuchsia: the expansion of the flowers, in the evening only, of Common Enothera

(Enothera biennis), hence called Evening Primrose: the silky coma surrounding the top of the seeds of the Willow-herbs.

24. Natural Order

Family.

DISTRIBUTION.-Tropical and temperate regions of both hemispheres; most numerous in America.—British genera 2, species 3.

Herbs. Flowers regular. Stamens 6 or 12. Ovary superior. Type-Purple Loosestrife (Lythrum Salicaria).

A perennial erect herb, with opposite or verticillate entire leaves, and terminal spicate rose or purple flowers.

OBSERVE the six teeth alternating with the free extremities of the coherent sepals, so that there appear to be twelve sepals cohering to form the calyx: the relative length of stamens and style in the flowers of different plants of Purple Loosestrife. Mr. Darwin pointed out that the stamens in this species are of three lengthslong, medium, and short. But two lengths only occur on the same plant, there being two sets of six in each flower. The styles also are of three corresponding lengths-long, medium, and short; and as they are never associated with stamens of corresponding length, we have three forms of flower :-No. 1, with short and medium stamens, and long style; No. 2, short and long stamens, and

medium style, as in Fig. 110; and No. 3, with medium and long stamens, and short style. Mr. Darwin's experiments indicate that it is of advantage to the plant to

FIG. 110.-Vertical section of flower of Purple Loosestr.fe.

have the stigma fertilized by pollen from stamens of corresponding length, which necessarily involves the aid of insects, as these are borne not only by a different flower, but also upon a different plant.

Henna, used by Egyptian ladies to dye their nails and the palms of the hand a reddish-brown colour, is obtained from the leaves of Lawsonia inermis. The nails of mummies have been found stained in this way.

25. Natural Order- Cucurbitaceæ. Family.

The Gourd

DISTRIBUTION.-Tropical and warmer regions of both the Old and New World.-One British genus, species 1. Type-Common Bryony (Bryonia dioica).

A climbing perennial herb, with palmately-lobed leaves, extra-axillary tendrils, and diœcious flowers. (The only British species.)

OBSERVE the tendrils, often more or less extra-axillary, regarded as modified leaves of shoots, the internodes of which are undeveloped: the stamens, the anthers of four of which are confluent in two pairs. The anther-cells are remarkably sinuous in Bryony and many other genera of the Order, resembling the letter.

The Cucurbitaceæ are mostly tropical. Amongst them are several species extensively grown for the sake of their fruits, as the Gourd, Pumpkin, Cucumber, Melon, and Water-Melon.

The firm outer layer of the pericarp is often hollowed out, as in the Bottle-Gourd (Lagenaria), and used as a domestic utensil, or ornamented with figures burnt upon the surface. The fruit of the Gourd sometimes attains an enormous size: one raised in Norfolk, in 1846, weighed 196 pounds. The fibrous inner layer of the pericarp of the Towel-Gourd (Luffa ægyptiaca) is used as sponge and gun-wadding. Many species are intensely bitter, and some are dangerously poisonous, as the Colocynth (Citrullus colocynthis) and Squirting Cucumber (Momordica Elaterium, L.); the latter so called because the fruit, when quite ripe, separates suddenly from the peduncle, and the sides, forcibly contracting, squirt out the contained pulp with considerable force.