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excellence as architects. Their styles of nest-building are very various 

 indesign, but there is one characteristic running through all which dis- 

 tinguishes their nests from those of all others birds. Owing to the ex- 

 treme weakness of the feet and to the great length of the wings these 

 birds are excessively awkward in any situation but their native element, 

 the upper air. They cannot build of grass, feathers or hair mixed with 

 mud as so many other birds do. To collect the materials would be diffi- 

 cult to weave them together impossible. Neither can they nest upon 

 the ground — a common alternative, especially with non-perchmg birds, 

 get him on a solid, level surface and the swift is almost helpless. He 

 flounders awkwardly about until he can launch himself over the edge 

 of a rock or bank, and spread those long wings again on the free air. 

 But if nature has condemned this race to make bricks without straw, 

 she has herself shown them how to provide a substitute, and that from 

 a most unique source. The whole family are gifted with an unusual 

 development of the salivary glands which in nesting time secrete within 

 the mouth a thick viscous fluid. Of this material, wholly or in part, 

 the nests of all the various species of swift are composed. On ex" 

 posure to the air it soon dries into a glue-like substance, hard, light 

 and elastic. So tenacious is it that in removing the nest of our own 

 North American species from a chimney the very brick itself will often 

 come away in scales before the nest will break. Thus equipped these 

 children of the air are almost independent of the earth, and can fix 

 their homes and rear their young in the most inaccessible places, far 

 from the dangers of this lower world. 



In Ceylon and the islands of the Indian Archipelago several species 

 of the genus Collocalia fasten their little saucer-shaped egg-baskets 

 against high over-hanging cliffs, or on the walls of caverns running in 

 from the sea. These furnish the famous Salangane, or edible birds- 

 nests, so dear to the heart of the Chinese epicure. The best samples, 

 that is, the first of the season, are composed wholly of the salivary 

 gum, and are so difficult to obtain that they are frequently sold in the 

 Celestial Empire as high as three guineas ($15) a pound. In general 

 shape they resemble the nest of our own chimney swift, but are of a 

 translucent white colour, and appear as if woven of threads of 

 isinglass. 



