Page:Popular Science Monthly Volume 39.djvu/247

Rh the nervous filaments spread over their centers. These animals are not entirely insensible to the action of light; for they shrink from it and exhibit signs of being disagreeably affected when they are exposed to it.

The faculty of hearing is greatly developed among insects. The slightest noise disturbs them—yet the position of the organ of hearing has not been well defined. Maurice Girard assumes that its seat is in the antennaæ; and in the absence of a special organ, that it acts like a flexible rod, free at one end, and attached by the other end to an elastic membrane. M. Künckel agrees with Müller and Siebold that the organ of hearing is situated outside of the head.

The smell and the taste, on the other hand, belong entirely to the cephalic region. The taste is seated near the mouth; the smell is one of the appanages of the antennæ. This has been irrefutably demonstrated by M. Balbiani, who, taking a number of newly hatched male silkworm moths, and isolating them from contact with females, divided them into two lots, which he placed in different boxes. One of the lots was left undisturbed, the other was subjected to experiments. The pectinal antennæ of all the individuals in it were cut off at the roots. On bringing tables on which were females near the boxes containing undisturbed moths, the insects were observed, even at a distance of several yards, to beat their wings and become violently agitated. But when females were brought near the moths that had been deprived of their antennæ, they showed no signs of being affected; their wings remained flat and motionless. The strong exhalations from the females were imperceptible to them; the removal of their antennæ had deprived them of the power of smelling. Other naturalists, however, give the power of perceiving odors to the stigmata.

Locomotion is performed in insects, as in vertebrates, by means