22 INTRODUCTION TO ZOOLOGY. 



20. Describe the teeth in tlie crop. 



21. How many gastric ca3ca? What is their use? 



22. Is the intestine straight? 



23. Where are the ovaries? 



24. Wliat shape are the eggs? 



25. In what are the eggs enclosed? 



26. How many eggs did you find in the ovary? 



27. Did you see any immature eggs? 



28. How do the eggs escape from the bod}^? 



29. What is the oviduct? 



30. What is the ovipositor? How is it used? 



31. What are the urinary tubules? 



32. What are the internal breathing organs? 



33. Describe the structure of an air tube. 



34. From what do the air tubes run? 



35. Describe the branching of an air tube. 



36. To what parts of the body do the air tubes run? 



37. Is the grasshopper's system of breathing as good 



as ours? 



38. Where is tlie nervous system? 



39. Of what does the nervous system consist? 



40. Is the nerve cord double or single? 



41. How many ganglia in the body? 



42. Where are the largest muscles? 



Additional Facts About the Grasshopper. 



Tlie skeleton of the grasshopper consists of the 

 hard parts of the body, and these are on the outside. 

 It is therefore called an exoskeleton. It is composed 

 of a substance somewhat like horn, which is called 

 chitin. The teeth in the crop are composed of the 

 same material. The hard parts of tlie body are on 

 the outside, and growth cannot take place grad- 

 ually. Increase in size of the body cannot increase 

 the size of tlie hard skeleton. So, when a grasshopper 

 is growing up to full size, it sheds its skeleton four or 



