A Typical Insect 3 



convenient to take as our type a primitive kind of 

 insect, one in which the various parts of the body are 

 not very highly modified or specialised. Such an insect 

 is provided for us in the common Cockroach of our 

 kitchens (l). And as we examine its various organs, 

 we can compare with them the corresponding organs 

 in some higher insects, which have left the cockroach 

 far behind in the advance towards perfection of 

 structure. 



Fig. I. — The Common Cockroach {Blatta orientalis). a. Female ; 

 b. Male ; c. Female (side view) ; d. Young. Natxiral size. 

 From Marlatt, Bull. 4 (n.s.) Div. Ent. DepL Agric. U.S.A. 



A short examination of a Cockroach (fig. l) shows 

 us that it presents the threefold division of the body 

 mentioned above as characteristic of insects. There 

 is a distinct head, joined to the fore-body by a narrow 

 flexible neck, and bearing a pair of long feelers. The 

 fore-body (thorax) consists of three segments, each 

 of which carries a pair of legs, and each of the two 



