GNAT* 
471 
descend to the bottom, but are quickly obliged to 
return again to the surface in order to breathe, 
which they effect through a tubular orifice in the 
tail. The eggs from whence these insects proceed, 
are deposited by the parent animal in groups of 
several hundreds, enclosed in an unctuous matter, 
and placed on the surface of the water, and almost 
constantly in the vicinity of some aquatic plant. 
When the larvae have been nearly a month ex- 
cluded from the egg, during which time they feed 
on the minute animal and vegetable substances which 
abound in stagnant waters, they begin to change 
their form and turn into chrysalids. In this state 
they appear rolled up, except a portion of the tail 
which hangs down ; the upper part has a very un- 
couth appearance, and the rudiments of the future 
insect may be traced through the thin covering. 
The situation of the respiratory organs is com- 
pletely changed ; for, whereas in the larva the 
tail was the medium through which the animal 
breathed, in the chrysalis the same function is per- 
formed near the head ; a difference is likewise per- 
ceptible in the means, the larva breathing through 
one tube, while the chrysalis respires through two. 
From this state the gnat is transferred to another 
element, and becomes an inhabitant of a new world. 
In order to effect this change she struggles to break 
through her prison, bursts the chrysalis, and, re- 
signing the empty shell of the amphibious animal, 
springs into the air with a body actuated by a sur- 
prising agility, and with limbs of the finest texture. 
