334 TROPICAL NATURE 



tubular tongue out of one of the ordinary kind is easily con- 

 ceivable, as it only requires to be lengthened, and the two 

 laminae of which it is composed curled in at the sides ; and 

 these changes it probably goes through in the young birds. 



When on the Amazons I once had a nest brought me 

 containing two little unfledged humming-birds, apparently 

 not long hatched. Their beaks were not at all like those 

 of their parents, but short, triangular, and broad at the base, 

 just the form of the beak of a swallow or swift slightly 

 lengthened. Thinking (erroneously) that the young birds 

 were fed by their parents on honey, I tried to feed them with 

 a syrup made of honey and water, but though they kept their 

 mouths constantly open as if ravenously hungry, they would 

 not swallow the liquid, but threw it out again and sometimes 

 nearly choked themselves in the effort. At length I caught 

 some minute flies, and on dropping one of these into the open 

 mouth it instantly closed, the fly was gulped down and the 

 mouth opened again for more; and each took in this way 

 fifteen or twenty little flies in succession before it was satis- 

 fied. They lived thus three or four days, but required more 

 constant care than I could give them. These little birds 

 were in the "swift" stage; they were pure insect-eaters, 

 with a bill and mouth adapted for insect- eating only. At 

 that time I was not aware of the importance of the observa- 

 tion of the tongue; but as the bill was so short and the 

 tubular tongue not required, there can be little doubt that 

 the organ was, at that early stage of growth, short and flat, as 

 it is in the birds most nearly allied to them. 



Differences between Sun-birds and Humming-birds 

 In respect of all the essential and deep-seated points of 

 structure, which have been shown to offer such remarkable 

 similarities between the swifts and the humming-birds, the 

 sun-birds of the Eastern hemisphere differ totally from the 

 latter, while they agree with the passerine birds generally, or 

 more particularly with the creepers and honey-suckers. They 

 have a deeply-notched sternum ; they have twelve tail-feathers 

 in place of ten ; they have nineteen quills in place of sixteen ; 

 and the first quill instead of being the longest is the very 

 shortest of all, while the wings are short and round instead 



