LABORATORY WORK, VII 349 



vial of essence of heliotrope ; (3) a vial of cologne ; (4) a vial of di- 

 lute ammonia; (5) a glass-covered box about 8 inches cube. 



1. Offer to the spider the end of the glass rod, first clean, then dipped 

 in essence of heliotrope ; cleaned and dipped in cologne ; in ammonia. 

 Note and record movements. 



2. Place the spider in the box and note for ten minutes its instinc- 

 tive movements. 



3. Leave the spider in the box for a day or two and draw the web ; 

 in successive stages of formation if possible. 



TOPICS FOR FURTHER STUDY 



1. Habitat and food of Argiope and Theridium. 2. Distribution 

 of these spielers. 3. Spinning habits of spiders in general: forms of 

 webs and nests of the different classes of spiders ; economic impor- 

 tance of spiders' webs. 4. Biting and poisonous spiders. 



VII. CRAYFISH (Cambarus) 



Crayfish can be obtained from small streams in most parts of the 

 United States, except New England. They are also for sale in the 

 markets of large cities, and are easily transported and kept alive 

 for days in damp moss. They may eventually be transferred to an 

 aquarium containing water not more than an inch deep. Feed upon 

 earthworms or pieces of meat. The crayfish may be replaced by 

 the lobster. 



DRAWINGS 



1. View from left side, taking care to preserve accurately the pro- 

 portions, x 1.5. 



2. Ventral view. (Omitting legs.) x 1.5. 



3. Draw the posterior aspect of the following appendages of the 

 right side of animal, without removal from body, x 2. 



(a) small antenna. (g) 4th thoracic appendage. 



(&) large antenna. (//) 5th thoracic appendage. 



(c) mandible. (i) 8th (last) thoracic appendage. 



(c/) 1st maxilla. (&) 4th abdominal appendage 



(e) 2d maxilliped. (swimineret). 



(/) 3d maxilliped. (/) last abdominal appendage. 



