52 INSECTS. 



Internal Anatomy. Select for dissection large female 

 grasshoppers, the larger the better. On the Western 

 plains the lubber grasshopper (Brachystola magna), and 

 in the South the American locust (Schistocera americana), 

 will be obtainable, and will serve better than the Carolina 

 locust, because larger. Have specimens freshly killed in 

 the cyanide bottle. 



Do not begin a dissection when tired or nervous, for 

 eager eyes and steady nerves are necessary to success. 

 Should you injure some one organ in the first dissection, 

 and so not see it satisfactorily, make a special dissection 

 to find it in another specimen. 



Dissect the grasshopper on a shingle or bit of board. 1 

 Place it back uppermost, and head from you. Spread the 

 wings, and pin them so. Pin the last segment of the 

 abdomen firmly to the shingle. With sharp, fine-pointed 

 scissors, make a shallow cut through the skin of the abdo- 

 men, from the ovipositor forward, keeping some distance 

 to the left of the median line, and continue the cut for- 

 ward to the head along the thorax at the bases of the 

 left wings. Then with forceps gently lift the right-hand 

 edge of the skin above the abdomen, and look beneath it 

 for a delicate, whitish vessel, the dorsal vessel, sometimes 

 improperly called the heart. It is but a series of thin- 

 walled chambers, into which the blood flows through 

 lateral valves, and through which it progresses forward 

 toward the head. You will find the colorless blood bath- 

 ing all the internal organs. A microscopic examination 

 of a drop of it will reveal its white corpuscles. The 

 dorsal vessel lies close to the roof of the abdomen, is very 

 liable to be injured in the opening of the skin, and may 

 sometimes be best approached by a dissection from the 

 ventral side. Make a second cut similar to the first, 

 on the right of the median dorsal line of the body, and 

 1 Or under water, if preferred. See Appendix, p. 283. 



