NO. 9 OLFACTom- SENSE OF INSECTS McINDOO 55 



of the insects on which he experimented with the antenncC amputated 

 became sick and soon died. Most of them failed to respond when 

 the antennse were mutilated, although Carabus, Melolontha, and 

 Silpha responded slightly, while all the Ilemiptera that he used re- 

 sponded almost as well with their antenuce off as they did with them 

 intact. Only 40 per cent of tiie ants from which Miss Fielde cut 

 the antennre recovered from the eft'ect of the shock. Not one of" 

 these observers has studied the behavior of the species under obser- 

 vation sufficiently to know exactly how long they live in captivity 

 with their antennae either intact or mutilated. No one, except Miss 

 h'ielde. has kept a record of the death of the mutilated and normal 

 insects accurate enough so that one might know what percentage died 

 from the operation. To cut off some other appendage or even the 

 lower part of the head, as Forel did, is not a fair test, because such 

 o])erations seldom expose sense cells and never any nerve equal in 

 size to that of the antennae, unless one pulls off the wings. When 

 the wings are pulled off the large nerve is severed between the masses 

 of sense cells and thorax, and the sense cells are not exposed to the 

 air, as they are when antenna; are cut off. Even if the antennae are 

 cut through the scape, the large masses of sense cells belonging to 

 Johnston's organs are severed. When the lower part of the head or 

 the tarsi are cut off, as Forel did, no nerves are exposed to the air 

 except ends of small nerves. From the foregoing it is only reason- 

 able to assume that when the antennre of any insect are injured in the 

 least degree, the insect is no longer normal and if it fails to respond 

 to odors placed near it. this negative response may be caused by the 

 injury. 



The following criticisms based on a consideration of the morph- 

 ology of the antenna; may also be offered. In the honey bee the pore 

 plates can scarcely be considered as olfactory organs, because the 

 drone has almost eight times as many as the queen, and responds to 

 the odors presented in slightly more than one-half the time. It is 

 true that those of the queen are considerably larger, but even on this 

 basis the reaction times are not comparable. The pegs may be 

 entirely eliminated as olfactory organs, because they are absent in 

 the drone, but are abundant in the worker and the queen. Drones, 

 queens and workers have about the same number of Forel's flasks 

 and pit legs. Schenk's view that the pegs receive odor stimuli in the 

 queens and workers, while Forel's flasks and the pit pegs function 

 in this way in the drones is inconsistent, because if the latter two 

 structures function for such a purpose in the drones why should 



