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i 
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AUDITORY APPARATUS OF THE MOSQUITO. 587 
instrument until the fibril ceased to vibrate, and then drew a line 
on a piece of paper, under the microscope, in the direction of the 
fibril. On extending this line, I found that it always cut within 5° 
of the position of the source of the sound. The antennæ of the 
male mosquito have a range of motion in a horizontal direction, so 
that the angle included between them can vary considerably inside 
and outside of 40°,* and I conceive that this is the manner in 
which these insects during night direct their flight toward the 
female. * The song of the female vibrates the fibrillæ of one of the 
antenne more forcibly than those of the other. The insect spreads 
the angle between his antennz, and thus, as I have observed, 
brings the fibrillæ, situate within the angle formed by the antenne, 
in a direction approximately parallel to the axis of the body. The 
mosquito now turns his body in the direction of that antenna 
Whose fibrils are most affected, and thus gives greater intensity to 
the vibrations of the fibrils of the other antenna. When he has 
thus brought the vibrations of the antenne to equality of inten- 
sity, he has placed his body in the direction of the radiation of 
the sound, and he directs his flight accordingly ; and from my ex- 
periments it would appear that he can thus guide himself to within 
5? of the direction of the female. 
components, as is done by the higher vertebrates ; but I do not 
hold this view, but believe that the range of co-vibration of the 
fibrils of the mosquito is to enable it to apprehend the varying 
Pitch of the sounds of the female. In other words, the want of 
poin ite and fixed pitch to the female’s song demands for the re- 
ceiving apparatus of her sounds a corresponding range of co-vi- 
bration, so that instead of indicating a high order of auditory 
development it is really the lowest, except in its power of deter- 
mining the direction of a sonorous centre, in which respect it sur- 
Passes by far our own ear.} 
E Aeneas r ane T ES 
_ °The shafts of the ant i ut 40°. The basal fibrils of the 
Chee i ? antenna include an angle of abo A ale of about 30°, with 
the axis of the insect ; 
e insect, 
[seme Physiologists, attempting to explain the function of th i age 
» because these canals are in three planes at right angles to each other, that 
hey serve to fix in space a so just as th metrician by his three coör- 
dinate Planes determines the position of a point in space. But this assumption is fan- 
