MAEINE BOTANtf. 123 



and at every stage of civilization, man is led by an inner voice 

 to rely on the invisible powers, where a great and dangerous 

 enterprise is before him. The Salangane, as we have said, 

 builds its nest of sea- weed, which it macerates in its maw, 

 and then expels again through the beak. The layers are 

 continually placed on the edge of the nest till the whole is 

 finished, and they harden in the air. "When the time for 

 the harvest approaches, a few collectors go down into the 

 hole daily, and examine in what state the young brood is. 

 If they notice that the young are nearly all fledged, the 

 collecting is begun. These nests form the first quality; 

 those with still quite naked birds, the second ; while those 

 which still contain eggs, and are not ripe, are counted as the 

 third. On the other hand, those nests are over-ripe, black 

 and useless, in which the young are already feathered. All 

 the young and the eggs are thrown in the sea. The nests 

 are taken thrice a-year ; and the birds incubate four times. 

 In spite of this huge extermination, their number does not 

 decrease, either because many young birds have flown out 

 before the day of execution, or other swallows come from 

 caves that are still inaccessible. From this cave, 50 piculs 

 are annually obtained, for which the Chinese pay from £350 

 to £450, or about three guineas per pound. A picul, on the 

 average, contains 1,000 nests. If we assume each collection 

 to produce 50,000, and calculate two birds to each nest, we 

 arrive at a total of more than 100,000 swallows living 

 together in the Javanese ocean-caves. 



In the interior of the island, too, in the limestone grottoes 

 of Bandong, the Salangane nestles, though in much smaller 

 numbers, for scarce 14,000 nests are collected there in the 

 year. In these caves, swallows and bats live together, but 

 do not disturb each other ; for when they are not breeding, 

 the former fly out of the cave at sunrise and do not return 

 till late in the evening. The collectors suspect that they 

 seek the sea-beach. 



In Sumatra and the other Sunda isles, birds' nests are 



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