36 INSECTS ABROAD. 



intended to be employed against an enemy. The foe in question 

 is generally one of the larger CarabidsB, which would sood 

 devour the small and helpless Brachinus were it not deterred 

 by the repeated explosions and clouds of blue vapour that issue 

 from its expected prey. 



The fluid and the apparatus which secretes it have been 

 carefully investigated by M. Leon Dufour. Like most internal 

 organs, the secreting apparatus is double, one on either side of 

 the abdomen. M. Dufour describes the organ as consisting of 

 two distinct portions, one being the "preparatory organ" in 

 which it is secreted, and the other the "conservatory organ," in 

 which it is reserved until wanted. The actual secreting organs 

 are two slender fibres, which are in fact glands in their earliest 

 condition, and which open into the preparatory organ just 

 as the secreting organs of the bee or wasp open into the 

 poison-bag. 



The preparatory organ of the Brachinus assumes two very 

 different aspects, according to its degree of contraction or ex- 

 pansion. When contracted, it is a soft, round, opaque, whitish 

 body, situated under the last rings of the abdomen. When 

 expanded, it becomes oblong, translucent, filled with air, and 

 occupying nearly the full length of the abdomen. The reservoir, 

 or conservatory organ, does not alter its shape, but is always 

 small, globular, reddish-brown, tough in texture, hollow in the 

 inside, and placed within the last ring of the abdomen. Both 

 sexes possess this apparatus. 



As to the fluid itself, it is capable of staining the human skin 

 black, and that so deeply that the stain remains for several 

 days. Mr. Westwood, in his " Modern Classification of Insects," 

 gives the following anecdote, which was narrated to him by the 

 celebrated African traveller, Burchell : — 



" While resting for the night on the bank of one of the lame 

 Smith American rivers, he went out with a lantern to make an 

 astronomical observation, accompanied by one of his black 

 servant boys ; and, as they were proceeding, their attention was 

 directed to numerous Beetles running about upon the shore, 

 which, when captured, proved to be specimens of a large 

 species of Brachinus. On being seized, they immediately began 

 to play I'll' their artillery, burning and staining the flesh to such 

 a degree that only a lew specimens could be captured with the 



