472 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1920. 



to answer this question by carrying 450 Promethea cocoons from 

 Massachusetts to the Florida keys, where on separated small islands 

 the moths issued from the cocoons. This isolation insured that no 

 other individuals than those controlled by the experimenter could 

 confuse the observations. Some of the female moths were confined 

 in glass jars with the mouths covered with netting, while other 

 females were confined in glass jars turned upside down with the 

 mouths buried in sand. Males being released at various distances, 

 soon found their way to the jars whose mouths were covered with 

 netting, but no males came to the jars whose mouths were buried 

 in sand, although the moths in all the jars were plainly visible to 

 the experimenter. These experiments would seem to preclude 

 sight as a factor, and that the moths did not communicate with one 

 another by any such means as radiography or telepathy ; but if they 

 did, the agency used in the communication could not pass through 

 the glass jars. Therefore, it would seem that emanations passed 

 away from the jars whose mouths were covered with netting and 

 that these emanations were sensed in some way by the male moths. 

 The females of these giant silkworm moths, however, certainly have 

 highly developed scent-producing organs, and the males highly 

 developed olfactory organs, although they have not been described; 

 but in the common silkworm moths these organs are so highly de- 

 veloped that should the excised scent-producing organ be laid a 

 few inches from the female's body from which it was removed, the 

 male moths always neglect the nearby live female and go directly to 

 the scent-producing organ and try to copulate with it. 



THE SENSE OF SMELL AND TASTE COMBINED. 



Little experimental work has ever been performed to determine 

 whether insects have a true gustatory sense, although the sense 

 organs on the mouth parts of various insects have been studied con- 

 siderably. At least three different kinds of sense organs on the 

 mouth parts have been called organs of taste, but no one has ever 

 attempted to prove experimentally the function of these organs. 

 Judging from the fact that insects prefer some foods to others and 

 that certain insects often refuse poisoned foods, it is generally be- 

 lieved that insects can taste, regardless of whether or not they have 

 gustatory organs. 



At this place it is desirable to define the human senses of smell 

 and taste, so that we may use the definitions as a basis for inter- 

 preting the responses to the same or similar stimuli in honeybees, 

 which were used by the present writer to determine whether or not 

 insects have a true sense of taste. The sense of smell is called forth 

 by substances in a gaseous or vaporous condition, although gases 



