70 A GRASSHOPPER. 



a) A mass of yellow bodies occupying the dorsal region of the abdomen. 



These are the ovarian tubules and taken together constitute the 

 right and left ovaries, easily separable by a dissecting needle 

 along the median line. Each tubule is connected at one end with 

 the oviduct from that side, and is filled with eggs in various stages 

 of development. Mount some of the tubules and examine with 

 the compound microscope. Follow up the light-colored oviducts 

 and observe that they unite to form a single duct which leads to 

 the exterior opening at the base of the ventral pair of ovipositors. 

 Do the tubules stand vertically or do they slant in any way ? 



Exercise 8. Make a diagram of the reproductive system in an outline 

 of the abdomen. 



b) Note, in the thorax, the muscles which move the legs and wings. 



c) If your specimen is a fresh one you will have noticed a great many 



branching silvery tubes, the tracheae, and white, glistening air 

 sacs connected with them. By following up one of the larger 

 trunks its exterior opening can be identified with one of the 

 spiracles already noticed. That the branching tracheae penetrate to 

 every part of the body can be proven by examining the merest bit 

 of tissue under the microscope. What is the object of the spirally 

 wound thread that follows the inner wall of even the finer branches 

 of the tracheal system ? 



Exercise 9. Mount a piece of a tracheal tube on a slide, examine and 

 draw. 



d) After removing the reproductive organs free the underlying diges- 



tive tract from any tracheae or fatty tissue that conceals it. Note 

 its dark color due to contained food. The several parts of the 

 tract are, in their order, mouth, ossophagus, crop, ventriculus 

 and intestine. The crop is merely an enlargement of thecesopha- 

 gus. Its posterior border is not marked by any constriction, but is 

 just in front of the line of attachment of the curious double cone- 

 shaped pouches called gastric cceca. How many of these pouches 

 are there? It is from the crop that the live grasshopper ejects 

 "tobacco juice" when picked up. Why this habit? After you 



