But it is not so much his odd shape as a most extraordinary property he possesses, which is singularly unique in the animal kingdom, that makes him an object of interest and curiosity. Deep down in his most marvellous body a fluid, highly volatile in its nature, is elaborated, which the little creature can retain or expel at his pleasure. It is only, however, when alarmed that he utilizes this fluid in small quantities in defense, but its effect is wonderful, for in coming into contact with the atmosphere it immediately volatilizes and explodes, looking very much like a discharge of powder from a miniature artillery. In consequence of this phenomenon the insect which produces it is popularly called the Bombardier Beetle. [Illustration: BRACHINUS PURSUED BY AN ENEMY. His Curious and Unique Method of Defence.] So small a coleopter, being scarcely one-fourth of an inch in length, and so comparatively weak, is likely to be attacked by the larger Geodephaga, or Earth Devourers, and especially by the Carabi, which inhabit similar retreats. But for this curious defence the smaller insect could have but the barest chance of living in the struggle for existence. Often have I seen a Carabus in hot pursuit of Brachinus. The chase is always an interesting one, and never fails, however frequently it has been observed, of attracting attention and exciting admiration. But the wide-awake, ever watchful Brachinus never loses his head for a second when thus pursued, but like the clever artilleryman that he is, awaits the opportune moment, and then pours a heavy discharge of his fulminating fluid into the very face of the enemy. Baffled, alarmed, Carabus desists from the attack, and backs slowly away from the tiny blue smoke, while Brachinus, in the confusion that ensues, escapes to some place of security for rest and protection. Most skilfully has the artist delineated the scene. _Carabus serratus_, the pursuing beetle, is chasing the Bombardier, and has nearly effected his capture, when, all of a sudden, a discharge of artillery has stopped the pursuit, under cover of which the Bombardier will make off. Meanwhile the Carabus, exchanging his rapid advance for a retreat quite as rapid, throws back his antennæ, a sign of his defeat, and skulks away to recover his wonted self-possession.