346 ZOOLOGY 



DRAWINGS 



1. Imago, dorsal view, wings in place, x 10. 



2. Left side, showing stigmata ; wings having been removed and 

 preserved for further study, x 10. 



3. Front view of head, with antennae (lens), x 15. 



4. Posterior view of first pair of legs, x 15. 



5. Dorsal view of wing and balancer of the right side, x 15. 



6. Abdomen, ventral aspect, x 10. 



7. (Optional.) Egg of fly. x 10. 



8. (Optional.) Larva, side view, x 7. 



QUESTIONS ON EXTERNAL ANATOMY 



1. How many body-segments has the fly behind the head? 



2. How many segments in the antenna? 



3. How many segments in the leg ? (Compare with grasshopper.) 



4. Can you detect any difference between different individuals of 

 the same species in respect to form of the head and eyes ? 



OBSERVATIONS ON THE LIVING ANIMAL 



Each student should be provided with the following: (1) a bell- 

 jar (or any broad glass vessel) containing a fly and covered with a 

 card; (2) a soup-plate ; (3) vials of various colored, pungent, sweet, 

 and neutral substances, such as white sugar, vinegar, butter (prefer- 

 ably rancid), ground gypsum, white sugar reddened with carmine, |% 

 acetic acid, molasses. 



1. Place on the soup-plate at a little distance apart some sugar, 

 a drop of vinegar, grains of sugar, and a drop of water. Invert the 

 bell-jar containing a fly, over the soup-plate, and carefully move the 

 bell-jar until it covers all of the substances. Xote all the movements 

 of the fly for five minutes --these are the instinctive movements of the 

 fly in the given situation; note especially its movements with refer- 

 ence to the substances. 



2. Try the same fly with other combinations such as vinegar, mo- 

 lasses, water. 



3. Try a second fly with one of the same combinations of substances. 



