CHAPTER XXXVI.. Pollen.

POLLEN.

+Pollen+ and Farina, in the language of Botanists, are terms applied to the powdery particles discharged by the anthers of flowers in warm dry weather, and which hang about the stamina. The colour, as well as the structure of pollen, varies in different plants. Its use, in fecundating the germens of flowers, is well known: the services of bees, towards that end, will be noticed in a separate chapter. The sixth volume of the Linnæan Transactions contains an interesting paper upon this substance, from the pen of +Mr. Luke Howard+.

Pollen has a capsular structure, varying its shape in different flowers, insomuch as to be a popular object for the microscope. Each grain consists commonly of a membranous bag, which, when it has come to maturity, bursts on the application of moisture: this bursting is naturally effected by the honey-like exudation of the stigma; but if extraneous moisture accomplish it prematurely, the pollen is rendered useless for the purpose of fructification. Whenever moistened, the bag explodes with great force, and discharges a subtle vapour or essence, which, when released by the peculiar moisture of the stigma, performs effectually its final purpose.

This substance was once erroneously supposed to be the prime constituent of wax; but the experiments of +Hunter+ and +Huber+ have proved that wax is a secretion from the bodies of wax-working bees, and that the principal purpose of pollen is to nourish the embryo-bees; (it has been called the ambrosia of the hive). Huber was the first who suggested this idea, and it well accords with what we observe among other parts of the animal kingdom;--birds, for instance, feed their young with different food from what they take themselves. Mr. Hunter examined the stomachs of the maggot-bees, and found farina in all, but not a particle of honey in any of them. Huber considers the pollen as undergoing a peculiar elaboration in the stomachs of the nursing-bees, to be fitted for the nutriment of the larvæ.

"In spring," says +Dr. Evans+, "which may be called the bee's first carrying season, scarcely one of the labourers is seen returning to the hive, without a little ball or pellet of farina, on each of its hinder legs. These balls are invariably of the same colour as the anther-dust of the flowers then in bloom, the different tints of yellow, as pale, greenish or deep orange, being most prevalent." The bees may frequently be observed to roll their bodies on the flower, and then, brushing off the pollen which adheres to them, with their feet, form it into two masses, which they dispose of in the usual way. In very dry weather, when probably the particles of pollen cannot be made to cohere, I have often seen them return home so completely enveloped by it, as to give them the appearance of a different species of bee. The anther-dust, thus collected, is conveyed to the interior of the hive, and there brushed off by the collector or her companions. +Reaumur+ and others have observed, that bees prefer the morning for collecting this substance, most probably that the dew may assist them in the moulding of their little balls. "I have seen them abroad," says Reaumur, "gathering farina before it was light;" they continue thus occupied till about ten o'clock.

"Brush'd from each anther's crown, the mealy gold. With morning dew, the light fang'd artists mould. Fill with the foodful load their hollow'd thigh, And to their nurslings bear the rich supply."

+Evans.+

This is their practice during the warmer months; but in April and May, and at the settlement of a recent swarm, they carry pollen throughout the day; but even in these instances, the collection is made in places most likely to furnish the requisite moisture for moulding the pellets, namely, in shady and sometimes in very distant places.

When a bee has completed her loading, she returns to the hive, part of her cargo is instantly devoured by the nursing-bees, to be regurgitated for the use of the larvæ, and another part is stored in cells for future exigencies, in the following manner. The bee, while seeking a fit cell for her freight, makes a noise with her wings, as if to summon her fellow-citizens round her; she then fixes her two middle and her two hind legs upon the edge of the cell which she has selected, and curving her body, seizes the farina with her fore legs, and makes it drop into the cell: thus freed from her burthen, she hurries off to collect again. Another bee immediately packs the pollen, and kneads and works it down into the bottom of the cell, probably mixing a little honey with it, judging from the moist state in which she leaves it; an air-tight coating of varnish finishes this storing of pollen.

From the uniform colour of each collection, it is reasonable to suppose that the bee never visits more than one species of flower on the same journey; this was the opinion of +Aristotle+, and the generality of modern observers have confirmed it. +Reaumur+, however, supposed that the bee ranged from flowers of one species to those of another indiscriminately. +Mr. Arthur Dobbs+, in the Philosophical Transactions for 1752, states that he has repeatedly followed bees when collecting pollen; and that whatever flowers they first alighted upon decided their choice for that excursion, all other species being passed over unregarded: +Butler+ had previously asserted the same thing. Here we see the operation of a discriminating instinct, which in the first place leads the insect to make an aggregation of homogeneous particles, which of course form the closest cohesion; and in the next place prevents the multiplication of hybrid plants. This remark was made by +Sprengel+, who has confirmed the observations of Dobbs, Butler, and others. The bees, which Reaumur observed to visit flowers of different species, might have been in quest of honey as well as of pollen.