We may next notice the weaver (_Ploceus textor_) and tailor (_Prinia_, _Orthotomus_, and _Sylvia_). The former intertwines slender leaves of grass so as to produce a web sufficiently substantial for the protection of its young. The tailor-birds sew together leaves wherewith to make their nests, using for the purpose cotton and thread where they can find it, and natural vegetable fibres where they cannot obtain artificial. Colonel Sykes says that he has found the threads thus used for sewing knotted at the ends.[167] Forbes saw the tailor-bird of the East Indies constructing its nest, and observed it to choose a plant with large leaves, gather cotton which it regularly spun into a thread by means of its bill and claws, and then sew the leaves together, using its beak as a needle, or rather awl. This instinct is rendered particularly interesting to evolutionists from the fact that it is exhibited by three distinct genera. For, as the instinct is so peculiar and unique, it is not likely to have originated independently in the three genera, but must be regarded as almost certainly derived from a common ancestral type--thus showing that an instinct may be perpetuated unaltered after the differentiation of structure has proceeded beyond a specific distinction. The genus _Sylvia_ inhabits Italy, the other two inhabit India. _Sylvia_ uses for thread spiders' web collected from the egg-pouches, which is stitched through holes made in the edges of leaves, presumably with the beak. The baya bird of India 'hangs its pendulous dwelling from a projecting bough, twisting it with grass into a form somewhat resembling a bottle with a prolonged neck, the entrance being inverted, so as to baffle the approaches of its enemies, the tree snakes and other reptiles.' Sir E. Tennent, from whom this account is taken, adds:-- The natives assert that the male bird carries fire-flies to the nest, and fastens them to its sides by particles of soft mud. Mr. Layard assures me that although he has never succeeded in finding the fire-fly, the nest of the male bird (for the female occupies another during incubation) invariably contains a patch of mud on each side of the perch. Dr. Buchanan confirms the report of the natives here alluded to, and says:-- At night each of the habitations is lighted up by a fire-fly stuck on the top with a bit of clay. The nest consists of two rooms; sometimes there are three or four fire-flies, and their blaze in the little cells dazzles the eyes of the bats, which often kill the young of these birds.