162 THE MICROSCOPE. Nov. 



abdomen is the part which in the three types presents the 

 greatest dissimilarity. In the worker it is small and 

 oval, in the queen it is much longer and thicker, tapering 

 to a point, while in the drone it is short, stout and ob- 

 long, having the posterior part fringed with long stiff 

 hairs. 



Examine the head with reflected light and a low power. 

 There will be seen two compound eyes. Attached be- 

 tween these are two antennse and at the front is the 

 mouth. If a few of J^he hairs are removed from the 

 back of the head, three simple eyes may also be seen 

 (fig. 14, a). 



The eyes. — The two compound eyes consist of thirty- 

 two hundred single ocelli, each of which is composed of 

 two remarkably formed lenses : the outer or corneal (fig. 

 16, a), and the inner or conical (fig. 16, b). The cornea 

 is easily pealed off and the grouping of the lenses be- 

 comes distinctly visible. This corneal lens consists of 

 two plano-convex lenses of difl'erent densities and refract- 

 ing powers. The plane surfaces of these being adherent, 

 it follows that the prismatic corneal lens is a compound 

 double convex lens (fig. 16, a). How remarkable that 

 we should find this same construction in the most perfect 

 microscopical lenses of to-day. The light after it has 

 passed through the lens crosses the vacant space (fig. 16, 

 c) and enters the conical lens (fig. 16, b). This space 

 is surrounded with a dark pigment, which is narrowed 

 to form a round hole, like a diaphragm in a microscope). 

 The colored matter is continued downward and surrounds 

 the conical lens. This consists of a simple double con- 

 vex lens. At the apex it comes in contact with the bul- 

 bous expansion of the optic nerve (fig. 16, e), which ex- 

 tends in a line continuous with the axis of the ocelli 

 until it meets the nerve of the other eyelets. These 

 three unite to form a common trunk which communicates 

 with the insect's brain. Besides these compound eyes 



