THE BUTTERFLY. 39 



Observe that there are three somewhat distinct regions 

 in the body. These are named, in order, head, thorax, and 

 abdomen. 



Observe that the entire body is made up of rings or seg- 

 ments. How many segments are there in the thorax? In 

 the abdomen? 



Note now the external parts and appendages. 



1. The Head. 1. The long projections on the front of 

 the head are antennae. These also have segmented struc- 

 ture. Study them with the aid of a lens, and count their 

 segments. 



2. The large hemispherical prominences on the sides 

 of the head are the eyes, called also facets or compound 

 eyes, because they appear under magnification to be made 

 up of clustered simple eyes placed side by side. 



3. The two more or less hairy appendages in front of 

 and below the eyes are the labial palpi. Count their seg- 

 ments, and find their point of attachment to the head. 



4. The coiled organ between the palpi is the sucking 

 organ (or proboscis) . Uncoil it : how many turns in it ? 

 Notice the permanent bend near the middle of it. Ob- 

 serving that there is no oral opening on the surface of 

 the head, what structure will you expect to find within 

 this proboscis? 



With the microscope examine : 



1. A cross section of the proboscis. 1 



2. A tangential section of the surface (corneal layer) 

 of the eye. 2 Observe that the corneal layer seems to 



1 To make the cross section, place the proboscis uncoiled in a split 

 cork or between two pieces of elder or cornstalk pith, and, holding it 

 firmly there, with a razor or a very sharp knife shave off thin sections at 

 the end, shaving the holder and the proboscis together. 



2 Cut a section from the surface of- the eye. Holding the section with 

 fofceps by one edge, scrape out the dark-colored pigment from its inner 

 concave surface. Place it on a slide, convex surface uppermost, and it 

 is ready for examination. Use low power. 



