Reactio7is of the Po^nace Fly to Odorous Substances 531 



hair brush, which in turn was held in place by a small rubber band. 

 Secured in this way under the lens of a high-power dissecting 

 microscope, the third joints of the antennae were cut off by a pair 

 of fine embryological dissecting scissors. There is a deep division 

 between the second and third segments of the antenna, and the 

 third segment was usually removed without injury to the second. 

 After the effect of the ether^ had passed away, the fly operated 

 upon seemed in most respects perfectly normal. Such flies were 

 left for twenty-four hours without food, but were supplied with 



Fig. 5 Front view of the head of Drosophila showing in dotted lines the position of the olfactory pit 

 in the terminal segment of the left antenna. 



water. At the end of this time they were liberated singly in the 

 large cylinder used in the experiments described on p. 516, and 

 were carefully watched for five minutes in order to be certain that 

 their behavior was normal. Having ascertained this, their ability 

 to find a piece of fermenting banana in the cylinder was tested. 

 The time required to find the food was recorded, or if the food 

 was not found in fifteen minutes, the experiment was discontinued. 



' It should be noted that the process of etherizing has no lasting effect on the ability of the flies to scent 

 food, /. e., normal flies after recovery from ether find food with as great certainty as they did before 

 etherization. 



