(b) The thorax.—Notice the overlapping fore-wings (wing-covers). Pull them aside with forceps; notice that they are narrow and rather stiff, make out their points of attachment at the corners of the second segment of the thorax, and then cut them off with scissors. Pull out the delicate hind-wings in the same way, carefully noticing their fanlike method of folding, and their points of attachment to the corners of the third segment of the thorax. Stretch one out, cover it with a piece of glass to flatten it, and then draw it, marking the lines of folding. (Notice that some cockroaches of the common species found in kitchens are destitute of wings, and have only very small wing-covers. These are females.) After removal of the wing-covers and wings, the three segments of the thorax are very distinct. Notice that each segment bears a pair of legs. Take off one of the legs and draw it. How many joints has it? What is the use of its bristles? (c) The abdomen.—Observe the line which runs along the dorsal middle line of the abdomen; this marks the position of the heart. Examine the method of telescoping of the segments of the abdomen, and the soft membrane which connects the dorsal and ventral plates of each segment. Notice that the abdomen bears neither wings nor legs. Observe the pair of short palp-like bodies (cer., Fig. 223) at the end of the abdomen, and between them, in the male, a pair of more slender styles. In the female observe the boat-shaped “brood-chamber” (Fig. 223, st. 7), on the ventral surface. (d) The spiracles.—In the thin membrane between the dorsal and ventral plates, at the junction of two abdominal segments, look for a small hole (spiracle) leading into the interior of the body. How many [Pg 351] abdominal spiracles can you find on each side? Observe the two larger spiracles on each side of the thorax, between the first and second, and the second and third legs.