And young Lampyris, l. 288. The fire-fly is at some seasons so luminous, that M. Merian says, that by putting two of them under a glass, she was able to draw her figures of them by night. Whether the light of this and of other insects be caused by their amatorial passion, and thus assists them to find each other; or is caused by respiration, which is so analogous to combustion; or to a tendency to putridity, as in dead fish and rotten wood, is still to be investigated; see Botanic Garden, Vol. I. Additional Note IX.[Back to Canto]
Untasted honey, l. 302. The numerous moths and butterflies seem to pass from a reptile leaf-eating state, and to acquire wings to flit in air, with a proboscis to gain honey for their food along with their organs of reproduction, solely for the purpose of propagating their species by sexual intercourse, as they die when that is completed. By the use of their wings they have access to each other on different branches or on different vegetables, and by living upon honey probably acquire a higher degree of animation, and thus seem to resemble the anthers of flowers, which probably are supported by honey only, and thence acquire greater sensibility; see Note on [Vallisneria], l. 280 of this Canto.
A naturalist, who had studied this subject, thought it not impossible that the first insects were the anthers and stigmas of flowers, which had by some means loosened themselves from their parent plant, like the male flowers of vallisneria, and that other insects in process of time had been formed from these, some acquiring wings, others fins, and others claws, from their ceaseless efforts to procure food or to secure themselves from injury. He contends, that none of these changes are more incomprehensible than the transformation of caterpillars into butterflies; see Botanic Garden, Vol. I. Additional Note XXXIX.[Back to Canto]
There the hoarse stag, l. 321. A great want of one part of the animal world has consisted in the desire of the exclusive possession of the females; and these have acquired weapons to combat each other for this purpose, as the very thick shield-like horny skin on the shoulder of the boar is a defence only against animals of his own species, who strike obliquely upwards, nor are his tushes for other purposes, except to defend himself, as he is not naturally a carnivorous animal. So the horns of the stag are sharp to offend his adversary, but are branched for the purpose of parrying or receiving the thrusts of horns similar to his own, and have therefore been formed for the purpose of combating other stags for the exclusive possession of the females, who are observed, like the ladies in the times of chivalry, to attend the car of the victor.
The birds, which do not carry food to their young, and do not therefore marry, are armed with spurs for the purpose of fighting for the exclusive possession of the females, as cocks and quails. It is certain that these weapons are not provided for their defence against other adversaries, because the females of these species are without this armour; Zoonomia, Sect. XXXIX. 4, 8.[Back to Canto]
The incumbent Linnet, l. 348. The affection of the unexperienced and untaught bird to its egg, which induces it to sit days and weeks upon it to warm the enclosed embryon, is a matter of great difficulty to explain; See Additional Note [IX]. on Storge. Concerning the fabrication of their nests, see Zoonomia, Sect. XVI. 13. on instinct.[Back to Canto]
Hears the young prisoner, l. 351. The air-vessel at the broad end of an incubated egg gradually extends its edges along the sides of the shell, as the chick enlarges, but is at the same time applied closer to the internal surface of the shell; when the time of hatching approaches the chick is liable to break this air-bag with its beak, and thence begin to breathe and to chirp; at this time the edges of the enlarged air-bag extend so as to cover internally one hemisphere of the egg; and as one half of the external shell is thus moist, and the other half dry, as soon as the mother hearing the chick chirp, or the chick itself wanting respirable air, strikes the egg, about its equatorial line, it breaks into two hemispheres, and liberates the prisoner.[Back to Canto]
And whisper to the song, l. 356. A curious circumstance is mentioned by Kircherus de Musurgia, in his Chapter de Lusciniis. "That the young nightingales, that are hatched under other birds, never sing till they are instructed by the company of other nightingales." And Johnston affirms, that the nightingales that visit Scotland, have not the same harmony as those of Italy, (Pennant's Zoology, octavo, p. 255), which would lead us to suspect, that the singing of birds, like human music, is an artificial language rather than a natural expression of passion.[Back to Canto]
With undulating train, l. 373. The side fins of fish seem to be chiefly used to poise them; as they turn upon their backs immediately when killed, the air-bladder assists them perhaps to rise or descend by its possessing the power to condense the air in it by muscular contraction; and it is possible, that at great depths in the ocean the air in this receptacle may by the great pressure of the incumbent water become condensed into so small a space, as to cease to be useful to the animal, which was possibly the cause of the death of Mr. Day in his diving ship. See note on Ulva, Botan. Gard. V. II.
The progressive motion of fish beneath the water is produced principally by the undulation of their tails. One oblique plain of a part of the tail on the right side of the fish strikes the water at the same time that another oblique plain strikes it on the left side, hence in respect to moving to the right or left these percussions of the water counteract each other, but they coincide in respect to the progression of the fish; this power seems to be better applied to push forwards a body in water, than the oars of boats, as the particles of water recede from the stroke of the oar, whence the comparative power acquired is but as the difference of velocity between the striking oar and the receding water. So a ship moves swifter with an oblique wind, than with a wind of the same velocity exactly behind it; and the common windmill sail placed obliquely to the wind is more powerful than one which directly recedes from it. Might not some machinery resembling the tails of fish be placed behind a boat, so as to be moved with greater effect than common oars, by the force of wind or steam, or perhaps by hand?[Back to Canto]