BEHAVIOR OF SPIDERS AND OTHER INSECTS 437 



neither to the vibrations of the wings, nor to the pulsations 

 of the thorax, nor to special modifications of the occlusor appar- 

 atus of the stigmata, nor to movements of the halteres; but, 

 to a special sound-producing apparatus which is situated, on 

 each side of the thorax, near the base of the wings. This con- 

 sists of a membrane-lined depression which is traversed diagon- 

 ally by two ridges or ribs. When the wings are vibrated rapidly 

 a chitinous structure on the base of each strikes against one of 

 the ridges of the apparatus just described and induces the mem- 

 brane to vibrate. This produces the high pitched sound we call 

 buzzing. The following results of his experiments on the drone- 

 fly (Eristalis tenax) seem to justify his conclusion: — 1. The fly 

 may be held in the fingers in any way but one without appre- 

 ciably affecting the buzzing; press the shoulders of the wings 

 to the body and the buzzing ceases immediately. 2. Each or 

 all of the following parts may be removed without noticeably 

 affecting the sound; halteres, squama, ante-squama, aulet and 

 nine-tenths of the wing. If the entire wing is removed the 

 sound ceases. 3. If the vibrations of the aulets be checked 

 by a needle applied at tKe convexity of the chitinous part, the 

 sound continues. 4. If, while the fly is buzzing, a needle is 

 inserted between the chitinous part of the wing base and the 

 ribs on the body of the fly, although the parts are uninjured, 

 the buzzing ceases. 5. A minute spear of tissue paper inserted 

 between the chitinous portion of the base of the wing and the 

 ribs on the thorax subdues the sound. 6. If pins be so placed 

 that, without injuring the wings, they prevent them from closing 

 closer than 45° with the axis of the body, no buzzing is heard. 

 Evidently this organ is of a higher order than the striduiating 

 apparatus of the Orthoptera. Since a portion of it consists 

 of a vibrating membrane, Aubin is inclined to believe that it 

 is a sound-receptor as well as a sound-producer. 



In the discussion which followed the reading of this paper 

 before the Royal Microscopical Society of London, a Mr. Hop- 

 kins arose and stated that, eighty years age, Burmeister had 

 performed similar experiments which yielded identical results, 

 and he wondered why Aubin had not cited Burmeister's ex- 

 periments. At this writing, Burmeister's original paper is not 

 accessible to the present writer; but, judging from the quotation 

 made at the meeting of the society, Burmeister held that certain 



