LABORATORY WORK, VIII 351 



4. To the tip of one of the large antennae and to the small antennae 

 apply (a) the point of a needle; (/;) the vapor of ammonia; (c) a 

 drop of water; (d) a drop of 5% acetic acid. Tests () and (ft) should 

 be performed upon the antenna of one side and (rt), (c), and (d) upon 

 that of the other. Record the results. What inferences do you draw ? 



5. Wave the hand over the crayfish. Does it react ? If possible 

 flash a light at its head. Can the crayfish see? Cover the eye-stalks 

 with wax. Does it still react to a movement of the hand? 



TOPICS FOR FURTHER STUDY 



1. The habitat and food of the crayfish. 2. The geographical dis- 

 tribution of crayfishes. 3. Other stalk-eyed Crustacea (long and short 

 tailed) ; lobsters, shrimps, hermit-crabs, spider-crabs, edible crabs. 

 4. Economic importance of stalk-eyed Crustacea. 5. The breeding 

 habits and general development of crayfish and lobster. 6. The 

 capacity for regeneration in the higher Crustacea and the occurrence 

 of monstrosities. 7. Division of labor in the appendages of the cray- 

 fish. 



VIII. DAPHNIA 



Daphnia may be obtained from pools at almost any time of the year 

 except midwinter. They may be reared in large numbers in aquaria 

 properly stocked with decaying plants, upon which they feed. Select 

 for class work the largest individuals (females), which may attain a 

 length of 2 mm. 



DRAWING 



Place a living animal on a slide under a cover-glass, and with the 

 aid of the simple microscope draw a side view, x 20. 



OBSERVATIONS ON THE LIVING ANIMAL 



Each student should be provided with the following : (1) Stender 

 dish ; (2) pipette ; (3) watch-glass containing Daphnias ; (4) three 

 pieces of glass tubing 20 cm. long and 4 mm. bore, with two corks 

 to fit. 



1. Place a Daphnia in the straight glass tube (6) filled with clear 

 water and corked at both ends. (Exclude air-bubbles in corking.) 

 Place parallel to the rays from the source of light (preferably lamp 



