This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1860 edition. Excerpt: . LETTER V. THE ANTENNA OR FEELERS OF THE FLY j THEIR STRUCTURE, AND VARIOUS THEORIES REGARDING THEIR FUNCTIONS.

--THE EYES, COMPOUND AND SIMPLE; THEIR STRUCTURE AND USES. There is perhaps not a more interesting object in the animal creation than the head of a common Housefly. If you take a lens, and examine it carefully, you will find in front of the forehead a pair of short antennae or feelers (PL IV. fig. 1, a, a), organs which, in some of the insect races, impart those wonderful instinctive properties that have in this respect raised their possessors to a level with the so-called higher animals, and have rendered them a complete mystery to the naturalist. The antennae of a fly are well worthy of a particular description; they are composed apparently of three, but really of six joints, the third of which (PI. VI. fig.

2) is dilated and much larger than the rest; whilst the sixth is furnished with an arborescent tuft of bristles, and is termed a plumose joint. When the fly is at rest, the first three joints he in a depression of the insects head (PI. IV. fig. 1, a, a), whilst the plumose joint is seen to protrude: the object of this is probably, that the third joint, which we shall find to be the most important and delicately organized, should thus be protected from dust and other causes of injury. The principal feature of interest in the antennae is, that the third joint, when magnified, is found to be perforated all over with minute punctures; these are in reality (as a high magnifying power reveals, after the antenna has been bleached with chlorine) a series of microscopic sacculi (little sacs) extending inwards, and closed in from the air by a very thin membrane, and between these sacculi there are interspersed on the surface a great.