tion, other authors are inclined to place it in the tracheæ, either in their external margins or interior ramifications. Cuvier is of opinion that they are very well calculated to perform the office, the internal membrane being soft and moist, and fitted to receive odours from the air.[1] It must be admitted, that this hypothesis receives no support from the experiments of Huber, who found that bees were insensible to the smell of oil of turpentine, which they particularly dislike, unless it was applied to the base of the trunk near the cavity of the mouth. But the experiments of Lehmann afforded opposite results, and Huber's observations must therefore be considered inconclusive. Upon the whole, we have not sufficient grounds to come to any decision on the subject, although the probability is in favour of the tracheæ being organs of smell as well as of respiration.
The organs of sight are usually large and conspicuous, forming, as it were, the lateral portions of the cranium, sometimes meeting at their inner edges, and thus occupying greater part of the head. Owing to their structure, they have received the name of compound eyes, and they are often aided in their functions by another sort, in the form of small chrystalline points placed on the forehead, which are called simple eyes, ocelli, or stemmata. When present, the latter are generally three in number, placed in the form of a triangle on the crown; sometimes there are
- ↑ There really does exist, notwithstanding Kirby and Spence's assertion to the contrary, an internal membrane, although it is very thin and closely adherent to the spiral thread.
