"No, none that I can remember."
"Look again. Would he look natural whirling down into a chimney just at evening?"
"What! Do you mean a chimney-swallow, Jack?"
"That is precisely what I mean. Yes, Tom, these nests, which are such a peculiar delicacy to Chinese palates, are all made by swallows, and there are, as far as I can trace them, four species which build nests of this sort. They belong to a division of the swallows which are sometimes called swifts, our common chimney-swallow of the United States being included among the swifts. Those which build the edible nests are found only on the islands of this Asiatic region, and mostly on the coasts of the islands, though sometimes they go forty or fifty miles inland. They are all of one genus, Collocalia, and this one in my hand, which I shot myself, is the Collocalia fuciphaga.
"Four years ago I made a run down to the north coast of Java, and it was there I obtained these, the nests and the birds. The coast on that part of the island is very rocky, and large caves exist in some places, penetrating the rocks quite deeply. I knew that these caves were said to be specially frequented by the swallows, and I found that the report was true, for I visited five or six of them. The birds were very abundant, and I had opportunity to see their nests in every stage of their history. I brought away these three as fair representatives. You can see how they were placed, and this engraving gives you a correct idea of it. They were actually stuck against the perpendicular or sloping wall of rock, precisely as a chimney-swallow sticks his nest against the side of a chimney, his, however, consisting only of a worthless mass of twigs. The Chinamen gather them from these places in boat-loads, and bring them to market. Most of those which are brought here come, I think, from Java and Borneo, though a good supply is obtained also in Ceylon, the species which is found there being the Collocalia nidifica. The nests, however, of the different species are sold together, the only distinction being in quality as to cleanness and color.
"Of course the value of the nests, as with all other goods, depends upon the quality. This dirty fellow here, which has evidently done its work, and furnished board and lodging to a rising family, is of small value; and yet even such as these Chinese patience and ingenuity can clean and clear so perfectly that they are fit for use, though never becoming of first class. This next one had not been used for rearing a brood, but it was soiled in some way in the building, and is of about middle grade. But this is what we call a prime article, this light one, and the whiter it is the better price it commands. The best are worth more than their weight in silver."
"But of what do the birds build them, Jack? Where do they get any such material? It is a strange-looking substance."
"No more strange than honey, Tom, and made in the same way. It used to be thought that it was something which the birds gathered from the surface of the sea, but we know now that that is all foolishness. I saw the swallows catching flies as industriously as I ever watched the barn-swallows doing it over the Green in New Haven, and I opened the stomachs of many specimens which I shot, and found them always filled with insects, and with nothing else, so that we know that their food is the same as that of other birds of their tribe.
"But they have a set of glands, corresponding to the salivary glands at the sides of the mouth, which form this peculiar gelatinous material used by them in building their nests. You know the song says, 'Little by little the bird builds its best,' and that is the way they deposit these fine fibres. When first placed they are always clear and nearly white, and of course nests gathered in that condition are highly prized; few, however, are obtained that have not been more or less soiled. I do not understand the mystery of Man Lok's art, but I know that bird's-nest soup is made very much as any other form of such material—say isinglass or gelatine—would be prepared for the table."