156 LIFE, IN ITS INTERMEDIATE FORMS. 
The power of these organs, so delicate and filmy in 
appearance, w'e have before alluded to, but it may be illus- 
trated by another anecdote. Leeuwenhoek has recorded 
a remarkable instance, in which ho was an eyewitness of 
the comparative capabilities of the Dragon-fly and the 
Swallow, as relates to the perfection of their flight. The 
bird and the insect were both confined in a menagerie 
about a hundred feet long ; and apparently their powers 
were fairly tested. The swallow was in full pursuit, but 
the insect flew with such astonishing velocity, that this 
bird of rapid flight and ready evolution was unable to 
overtake and entrap it ; the insect eluding every attempt, 
and being generally six feet before it. 
The organs of the mouth vary much in form and func- 
tion in different insects. In a Beetle they consist of two 
pairs of jaws, generally hooked and toothed, working hori- 
zontally, and an upper and an under lip, closing the mouth 
above and below. Each lower jaw bears one or two fila- 
ments, consisting of several joints ; and a similar pair is 
affixed to the lower lip. These filaments are called palpi, 
and are supposed to be highly endowed organs of touch. 
They greatly resemble the antenna 3, or horns of many 
joints, which project from tho front of the head; but 
these latter are considered to be organs of hearing. 
If we look at a Gnat piercing our hand with its blood- 
sucking tube, or a Butterfly pumping up the nectar of a 
flower through its spiral tongue, or a Fly dissolving grains 
of sugar with the fleshy lips of its proboscis, we shall not 
very readily allow them any analogy with tho apparatus 
of jaws and lips which we have just described. Yet great 
as is the dissimilarity, it is now established, that all these 
