THE TIBIA OF ANTS. 233 
straight down the tibia, and falls again into the main 
trachea just above the lower sac. 
The remarkable sacs (Fig. 9, ss) at the two ex- 
\remities of the trachea in the tibia may also be well 
seen in other transparent species, such, for -instance, 
as Myrmica ruginodis and Pheidole megacephala. 
At the place where the upper tracheal sac con- 
tracts (Fig. 9), there is, moreover, a conical striated 
organ (x), which is situated at the back of the leg, just 
at the apical end of the upper tracheal sac. The 
broad base lies against the external wall of the leg, and 
the fibres converge inwards. In some cases I thought 
I could perceive indications of bright rods, but I was 
never able to make them out very clearly. This also 
reminds us of a curious structure which is found in the 
tibiz of Lucustide, between the trachea, the nerve, 
and the outer wall, and which is well shown in some of 
Dr. Graber’s figures. 
On the whole, then, though the subject is still 
involved in doubt, I am disposed to think that ants 
perceive sounds which we cannot hear 
The Sense of Smell. 
I have also made a number of experiments on the 
power of smell possessed by ants. I dipped camel’s-hair 
brushes into peppermint-water, essence of cloves, laven- 
der-water, and other strong scents, and suspended them 
