40 THE INSECT WORLD. 
nearly the whole of the head. Some ‘have eyes of a brilliant 
green colour, but looked at in certain lights they appear red. 
Fig. 22 shows the head of the gnat with its two eyes, its antenne, 
and trunk. 
The instrument which the gnat employs for puncturing the 
skin, and which is called the trunk (Fig. 23), is well worthy of 
our attention. That which is generally seen is only the case of 
those instruments which are intended to pierce our skin and suck 
our blood, and in which they 
are held, as lancets and other 
instruments are held in a sur- 
geon’s case. The case (Fig. 24) 
is cylindrical, covered with 
scales, and terminates in a 
small knob. Split from end 
to end that it may open, it 
contains a perfect bundle of 
stings. Réaumur tried to ob- 
serve, by allowing himself to 
Faye oBERION: be stung by gnats, what took 
Pe Oy GLa See place during the attack. He 
forgot, in watching the operations of the insect, the slight pain 
caused by the wound, soliciting it as a favour, his only regret 
being not to obtain it when he wished. 
Réaumur observed that the compound sting, which is about a 
line in length, enters the skin to the depth of about three- 
quarters of a line, and that during that time the case bends into 
a bow, until the two ends meet. He noticed besides, that the 
trunk-case of certain gnats was even more complicated than that 
which we have described. But we will not dwell any longer on 
this point. 
Let us now try to give an idea of the construction and com- 
position of this sting, which after piercing the skin draws our 
blood. 
According to Réaumur, the sting of the gnat is composed of 
five parts. He acknowledges, however, that it is very difficult to 
be certain of the exact number of these parts, on account of the way 
in which they are united, and of their form. At the present day we 





