THE OLFACTORY ORGANS OF DIPTERA 459 
and consequently the preceding view has long since been aban- 
doned. Another old view was that the halteres aid in respiration 
Hicks and Lee regarded the structures as olfactory organs, while 
Leydig and Graber thought they were auditory in function. 
Weinland determined that the halteres in vibrating rapidly 
perform a number of different movements, and chiefly for this 
reason he thinks that the organs borne by them bring about the 
perception of movements, thereby steering the flight of the insect. 
He asserts that since the antennae bear the olfactory organs, the 
organs on the halteres certainly do not perform the same function. 
Nagel (’94), in commenting on the probable function of the 
halteres, thinks that the first four preceding views have been 
abandoned, but he is a strong advocate of Weinland’s view. 
The paper of Prashad (16) seems to be the most recent one 
concerning the sense organs on the halteres, and this author 
studied only the halteres of the mosquito, Ochlerotatus pseudo- 
taeniatus Giles. He evidently did not have access to most of 
the literature on this subject and consequently has added little 
knowledge concerning these organs. He thinks that each organ 
has an external opening’ and found two scalpel groups of pores 
on each halter, while the present writer found only one scalpel 
group on each halter of mosquitoes belonging to other genera. 
McEwen (18) has just recently observed the sense organs on 
the wings of Drosophila ampelophila. He determined “that 
these organs had nothing to do with the response to light’’ (pp. 
85 to 87), but performed no experiments using odor stimuli. 
To obtain material for the study of the disposition of the 
olfactory pores, dried museum specimens were largely used. 
These specimens were obtained of Messrs. C. T. Greene and C. H. 
Popenoe through the courtesy of Dr. L. O. Howard. Mr. 
Greene is furthermore to be thanked for verifying the identifi- 
cation of all the species used. Fresh material was fixed in the 
modified Carnoy’s fluid, and was embedded in eelloidin and 
paraffin. The sections were cut three and five microns in thick- 
ness, and weré stained in Ehrlich’s hematoxylin and eosin. All 
the drawings were made by the writer and all are original except 
figures 50 to 55; these represent the antennal organs of flies 
