98 A, M. Mayer— Researches in Acoustics. 
this statement and at the same time illustrate the manner in 
which these insects determine the direction of a sonorous 
sound of a tuning-fork, which an assistant placed in unknown 
positions around the microscope. I then rotated the stage of 
the —— until the fibril ceased to vibrate, and then drew 
ine a piece of paper, under the erie in the direc- 
tion of. the fibril. On extending this line, 1 found that it 
always cut within 5° of the position of the source of the sound. 
The antennz 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 con- 
ceive that this is the manner in which these insects during 
night direct their flight toward the female. The song of the 
female vibrates the fibrille of one of the antennz more forci- 
bly than those of the other, The insect spreads the angle be- 
tween his antenne, and thus, as I have observed, brings the 
fibrillz, situate within the angle formed uy the antenn, in a 
direction approximately parallel to the axis of the body. The 
mosquito now turns his body in the direction of that antenna 
has thus ake the vibrations of the antenns ne equality of 
matey he has placed his body in the direction of the radia- 
* the sound, and he directs his flight accordingly ; and 
experiments it would appear that he can thus guide 
himself to within 5° of the chrection of the female. 
of —— so that instead of indicating a heh order of 
auditory development it is really the lowest, except in its 
power of determining the direction of a sonorous center, in 
which respect it surpasses by far our own ear.t+ 
* The shafts of the coop include an angle of about 40°. The basal fibrils of 
the antennz form en f about 90°, and the terminal fibrils an angle of about 
30°, with the axis of the 
1 nals 
assume, becai ne ae aoe Sr ples ogi sgh teach ohn a 
they serve to fix in space a sonorous center, just as the his three 
i i position of a point in space. But thi 
is fanciful and entirely devoid of reason ; Be re coals aie alwnye in 
ie a ie 
