334 
TROPICAL NATURE 
IV 
tubular tongue out of one of the ordinary kind is easily con- 
ceivable, as it only requires to be lengthened, and the two 
laminse 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 Sm-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 
