l02 W. WESCHE ON SOME NEW SENSE-ORGANS IN DIPTERA. 



of this sense a general raptorial character? They are not 

 secondary sexual organs, as they are found on both sexes in an 

 equal state of development. 



A curious point is that these organs seem correlated with 

 a change in the mouth-parts. The majority of the Erupidae, 

 Empis, Silara, Iihamphomyia, have strong maxillae, or rather 

 the blades (laciniae) of that organ, canying near their bases 

 the maxillary palpi. In Hybos the laciniae are absent or 

 adhering to the labium ; the carclines are present as in Muscidae, 

 and the palpi are labial ; and the other two species are but 

 little modified from this type. None of these facts throw 

 any light on the subject under discussion, and I am again 

 obliged to leave the function of these organs without explanation. 

 Before arriving at this result I made the following experiments. 

 I found that with reflected light, focussed by means of a 

 "bull's-eye" condenser, |-in. objective, and a 10-in. tube, I 

 could just see the cilia on the tibia of Hybos. The insect was 

 pinned and had been in my cabinet for at least three years,, 

 which was probably a serious defect in the experiment. I 

 sounded tuning forks giving 518, 530, and 540 vibrations 

 a second, but could see no sympathetic movement in the cilia. 

 I then separately sounded all the notes of the chromatic scale 

 through several octaves of a powerful grand pianoforte, fully 

 open, the fifth octave C giving 540 vibrations, but with no 

 better success. As a confirmatory experiment I tried Culex 

 annulatus, J, but with a like negative result. In Meyer's ex- 

 periment a live insect was used, and his fork gave 512 vibrations 

 in a second.* 



Summary: (1) Both the antennae and palpi of insects are 

 capable of receiving the stimulus of several senses. 



(2) Their capacities differ greatly in different species, and con- 

 sequently a general rule is an impossibility. 



(3) Taste hairs, homologous with Kraepelin's taste hairs 

 in the Muscidae, are found in different orders of insects : in 

 the Orthoptera, Blatta orientalis ; Mecaptera, Panorpa com- 

 munis', Coleoptera, PhUonthus varius, Coprophilus striatal" s ; 

 Diptera, Galliphora erythrocephala, and a large number of 

 families; Hymenoptera, Ve*pa vulgaris, V. crabro, Apis melifica, 

 Bombus. 



* , 



Si rises of Animals, \\ 110. 



