74

EDIBLE FRUITS. COLOURS.

[CHAP. dense, sometimes almost stony, covering, so that it escapes digestion, while its germination is perhaps hastened by the heat of the animal's body. It may be said that the skin of apple and pear pips is comparatively soft; but then they are embedded in a stringy core, which is seldom eaten.

These coloured fruits form a considerable part of the food of monkeys in the tropical regions of the earth, and we can, I think, hardly doubt that these animals are guided by the colours, just as we are, in selecting the ripe fruit. This has a curious bearing on an interesting question as to the power of distinguishing colour possessed by our ancestors in bygone times. Magnus and Geiger, relying on the well-known fact that the ancient languages are poor in words for colour, and that in the oldest books-as, for instance, in the Vedas, the Zendavesta, the Old Testament, and the writings of Homer and Hesiod-though the heavens are referred to over and over again, its blue colour is never dwelt on, have argued that the ancients were very deficient in the power of distinguishing colours, and especially blue. In our own country Mr. Gladstone has lent the weight of his great authority to the same conclusion. For my part I cannot accept this view. There are, it seems to me, very strong reasons against it, into which I cannot, of course, now enter; and though I should rely mainly on other considerations, the colours of fruits are not, I think, without significance. If monkeys and apes could distinguish them, surely we may infer that even the most savage of men could do so too. Zeuxis would never have deceived the birds if he had not had a fair perception of colour.

Iv.]

HOOKED SEEDS.

75

In these instances of coloured fruits, the fleshy edible part more or less surrounds the true seeds; in others the actual seeds themselves become edible. In the former the edible part serves as a temptation to animals; in the latter it is stored up for the use of the plant itself. When, therefore, the seeds themselves are edible they are generally protected by more or less hard or bitter envelopes, for instance the Horse Chestnut, Beech, Spanish Chestnut, Walnut, &c. That these seeds are used as food by squirrels and other animals is, however, by no means necessarily an evil to the plant, for the result is that they are often carried some distance and then dropped, or stored up and forgotten, so that in this way they get carried away from the parent tree.

In another class of instances animals, unconsciously or unwillingly, serve in the dispersion of seeds. These cases may be divided into two classes, those in which the fruits are provided with hooks, and those in which they are sticky. To the first class belong, among our common English plants, the Burdock (Lappa, Fig. 50, a); Agrimony (Agrimonia, Fig. 50, b); the Bur Parsley (Caucalis, Fig. 50, c); Enchanter's Nightshade (Circæa, Fig. 50, d); Goose Grass or Cleavers (Galium, Fig. 50, e), and some of the Forgetme-nots (Myosotis, Fig. 50, f). The hooks, moreover, are so arranged as to promote the removal of the fruits. In all these species the hooks, though beautifully formed, are small; but in some foreign species they become truly formidable. Two of the most remarkable are represented on page 77,-Martynia proboscidea (Fig. 51, b) and Harpagophyton procumbens (Fig. 51, a). Martynia is a plant of Louisiana, and if

76 BURDOCK. AGRIMONY. FORGET-ME-NOT. [CH.

a, burdock (Lappa); b, agrimony (Agrimonia); c, bur parsley (Caucalis); d, enchanter's nightshade (Circea); e, cleavers (Galium); f, forget-me-nots (Myosotis).

its fruits once get hold of an animal it is most difficult to remove them. Harpagophytum is a South African genus. The fruits are most formidable, and are said

a, Harpagophyton procumbens (natural size); b, Martynia proboscidea (natural size). sometimes even to kill lions. They roll about over the dry plains, and if they attach themselves to the skin,

78

STICKY SEEDS.

[CHAP.

the wretched animal tries to tear them out, and sometimes getting them into his mouth perishes miserably.

The cases in which the diffusion of fruits and seeds is effected by their being sticky are less numerous, and we have no well-marked instance among our native plants. The common Plumbago of South Europe is a case which many of you no doubt have observed. Other genera with the same mode of dispersion are Pittosporum, Pisonia, Boerhavia, Siegesbeckia, Grindelia, Drymaria, &c. There are comparatively few cases in which the same plant uses more than one of these modes of promoting the dispersion of its seeds, still there are some such instances. Thus in the common Burdock the seeds have a pappus, while the whole flower-head is provided with hooks which readily attach themselves to any passing animal. Asterothrix, as Hildebrand has pointed out, has three provisions for dispersion; it has a hollow appendage, a pappus, and a rough surface.

But perhaps it will be said that I have picked out special cases; that others could have been selected, which would not bear out, or perhaps would even negative, the inferences which have been indicated; that I have put the cart before the horse; that the Ash fruit has not a wing in order that it may be carried by the wind, or the Burdock hooks that the heads may be transported by animals, but that happening to have wings and hooks these seeds are thus transported. Now doubtless there are many points connected with seeds which are still unexplained; in fact it is because this is so that I was anxious to direct attention to the subject. Still I