DIPTERA. 



'37 



it may open, it contains a perfect bundle of stings. Reaumur tried 

 to observe, by allowing himself to be stung by gnats, what took 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. 



Reaumur 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 



Figs. 23 and : 

 nkofG 



Trunk of Gnat, magnified. 



Figs. 25, 26, 27. 

 Lancets of the Gnat. 



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 Reaumur, 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 

 know that there are six. Reaumur, as also Leuwenhoek, thought he 

 saw two in the form of a sword blade with three edges. These have 

 the points reversed, and are serrated on the convex side of the bend 

 (Fig. 25). To form an idea of the shape of the other points, the 

 reader should look at Figs. 26 and 27. He will then see that the 

 gnat's sting is a sword in miniature. 



The prick made by so fine a point as that of the sting of the gnat 



