SOME REACTIONS OF DROSOPHILA, WITH SPECIAL 

 REFERENCE TO CONVULSIVE REFLEXES. 



FREDERIC W. CARPENTER 



{Zoological Laboratory, University of Illinois.) 

 With One Figure. 



The behavior of the pomace fly (Drosophila ampelophila) in 

 respect to several kinds of stimulation has already been the sub- 

 ject of investigation. Barrows ('07) has recently shown that 

 the insect is positively chemotropic to certain strengths of odorous 

 substances occurring in fermenting fruit, such as alcohol, acetic 

 and lactic acids, and acetic ether. To hght varying in intensity 

 from 5 to 250 candlepowers Drosophila is positively phototropic; 

 and under the influence of gravity it is negatively geotropic (Car- 

 penter '05). 



In the present study of the reactions of Drosophila to stimuli 

 other than those just mentioned, attention was first directed to 

 the behavior of the insects when they pass from a region of opti- 

 mum temperature into regions relatively warm or cold. The flies 

 were confined in a flat glass box, 38 cm. long, 23 cm. wide, and 8 

 mm. deep. The edges of the box along the two sides and one end 

 were sealed with aquarium cement and enamel, and thus made 

 water-tight. At the unsealed end of the box a small opening was 

 left through which the flies could pass into the interior. All the 

 movements of the insects could readily be observed through the 

 glass, and the short distance that separated the roof and floor of 

 the box permitted the use of a hand lens when desired. 



In the temperature experiments the box was partially immersed 

 in water as shown in the accompanying sectional view of the 

 apparatus. 



The water could be heated by means of an alcohol lamp placed 

 beneath the vessel containing it, or it could be cooled by placing 

 in the vessel small pieces of ice. By arranging the apparatus so 



