THE CABBAGE BUTTERFLY 55 



in many of the segments by a double knot, or ganglia. Note 

 the smaller nerves that are given off from each pair of 

 ganglia. Trace the double cord to the head. Note that 

 the cords separate, one cord passing up the right side of 

 the esophagus and one up the left side. Note also that 

 the cords join again on top of the esophagus and that each 

 one is enlarged at the end to form a large double ganglion, 

 the brain. 



Make a diagram of the nervous system. 



E. TOPICS FOR FURTHER STUDY. Make a summary of 

 the points to be drawn from this exercise; namely, the 

 habits, habitats, food, and movements of the locust, the 

 divisions of the body, number and kinds of eyes, number of 

 legs, antennae and wings, the breathing organs, digestive 

 organs, circulatory organs, and organs of excretion. Fix 

 in the mind the position of this insect in the animal king- 

 dom. To what branch, class, order, family, genus, and 

 species does it belong ? Compare it with other members 

 of the Arthropoda; namely, spiders, lobsters, centipeds, 

 and insects. Make a summary of its leading characteristics. 



XVII. THE CABBAGE BUTTERFLY 



Materials. Specimens of cabbage butterfly, camel's hair brush, 

 alcohol, glass slides, cover glasses, compound microscope, hydro- 

 chloric acid, hypochlorite of sodium, carbolic acid crystals, oil of 

 turpentine, Canada balsam. 



Directions. (The large milkweed butterfly, or the white cab- 

 bage butterfly will answer for this exercise. The milkweed butterfly 

 is also known as the Monarch, and is figured in the text.) 



A. EXTERNAL FEATURES. Observe the divisions of the 

 body. Do they correspond to those of the locust? What 



