SUCKING INSECTS. 



195 



finest needles or lancets before the microscope, you 

 will easily see that they have visible breadth, and ap- 

 pear blunt, ragged, and dull.'* But Reaumur is not 

 a little surprised at this, for Leeuwenhoeck and him- 

 self found this fine point composed of several needles, 

 some of them barbed with teeth, as may be verified 

 by pressing the instrument between the fingers. The 

 magnified figures will give a clearer idea of the or- 

 gan than the most minute description. 



Magnified figures of the sucker of the gnat: a, the sucker In its sheath ; 

 6, half of the sheath broken off to show the sucker ; c, the sucker developed 

 to show its several parts ; d, the barbed point of one blade of the sucker. 



The sheath is composed of a flexible substance, 

 and is employed, it would appear, for supporting and 

 keeping steady the piercers during the process of 

 penetrating into the skin. Besides this, Swammer- 

 dam says, " I should think that the acute and hollow 

 extremity of the sheath is certainly introduced into 

 the wound, and by means thereof the gnat afterwards 

 sucks the blood, which running or ascending by 

 suction between these parts, is at length conveyed 



