Here a tiny moth hovers above the tempting chalice, and now settles upon it with eager tongue extended for the nectar at its centre. What an immediate and expressive welcome! No sooner has this little feathery body touched the filaments than the eager anthers are released from their pockets, and, springing inwards, clasp their little visitor, at the same time decorating him with their compliments of webby pollen (A, Fig. 5).
The nectary now drained of its sweets, the moth creeps or flutters to a second blossom, and its pollen-dusted body thus coming in contact with its stigma, cross-fertilization is accomplished. The pollen of the laurel differs from that of most of the Heath blooms, its grains being more or less adherent by a cobwebby connective which permeates the mass as indicated in my magnified representation (B, Fig. 5).
[Illustration: Fig. 5]
It is probable that an accessory cross-fertilization frequently results from a mass of the pollen falling directly upon the stigma of a neighboring blossom, or even upon its own stigma, but even in the latter case, as has been absolutely demonstrated as a general law by the experiments of Darwin, the pollen from a separate flower is almost invariably prepotent, and leads to the most perfect fruition, and thus to the survival of the fittest-the cross-fertilized. And, in any event, the insect is to be credited for the release of the tiny catapults by which the pollen is discharged. But the laurel may be considered as an exceptional example of the Heath family. Let us look at a more perfect type of the order to which it belongs, the globular blossom of the Andromeda (
[Illustration]
Only a short walk from my studio door in the country I recently observed its singular reception to the tiny black-and-white banded bee, which seems to be its especial companion, none the less constant and forgiving in spite of a hospitality which, from the human stand-point, would certainly seem rather discouraging. Fancy a morning call upon your particular friend. You knock at the door, and are immediately greeted at the threshold with a quart of sulphur thrown into your face. Yet this is precisely the experience of this patient little insect, which manifests no disposition to retaliate with the concealed weapon which on much less provocation he is quick to employ. Here he comes, eager for the fray. He alights upon one of the tiny bells scarce half the size of his body. Creeping down beneath it, he inserts his tongue into the narrowed opening. Instantly a copious shower of dust is poured down upon his face and body. But he has been used to it all his life, and by heredity he knows that this is Andromeda's peculiar whim, and is content to humor it for the sweet recompense which she bestows. The nectar drained, the insect, as dusty as a miller, visits another flower, but before he enters must of necessity first pay his toll of pollen to the drooping stigma which barely protrudes beneath the blossom's throat, and the expectant seed-pod above welcomes the good tidings with visions of fruition.
[Illustration: Fig. 6]
And how beautiful is the minute mechanical adaptation by which this end is accomplished! This species of Andromeda is a shrub of about four feet in height, its blossoms being borne in close panicled clusters at the summit of the branches. The individual flower is hardly more than an eighth of an inch in diameter. From one of three blossoms I made the accompanying series of three sectional drawings (Fig. 6). The first shows the remarkable interior arrangement of the ten stamens surrounding the pistil. The second presents a sectional view of these stamens, showing their peculiar S-shaped filaments and ring of anthers-one of the latter being shown separate at the right, with its two pores and exposed pollen. The freshly opened blossom discloses the entire ring of anthers in perfect equilibrium, each with its two orifices closed by close contact with the style, thus retaining the pollen. It will readily be seen that an insect's tongue, as indicated by the needle, in probing between them in search for nectar, must needs dislocate one or more of the anthers, and thus release their dusty contents, while the position of the stigma below is such as to escape all contact.
[Illustration]
