296 THE MICROSCOPE. 



rest is closely folded up in a deep fissure, on the under-surface of the 

 head. The proboscis at its base appears to be formed by the union 

 of the lacinia above, and the Idbium below, the latter forming the 

 chief portion of the organ, which is tenanted by dilated muscular lips. 

 In the Tabanus these are exceedingly large and broad, and are widely 

 expanded, to encompass the wound made by the insect with its lancet- 

 shaped mandibles in the skin of the animal it attacks. On their outer 

 surface they are fleshy and muscular, to fit them to be employed as 

 prehensile organs ; while on their inner they are more soft and delicate, 

 but thickly covered with rows of very minute stiff hairs, directed a little 

 backwards, and arranged closely together. There are very many rows 

 of these hairs on each of the lips ; and from their being arranged in a 

 similar direction, they are easily employed by the insect in scraping or 

 tearing delicate surfaces. It is by means of this curious structure that 

 the busy house-fly often occasions much mischief to the covers of our 

 books, by scraping off the white of egg and sugar varnish used to give 

 them the polish, leaving traces of its depredations in the soiled and 

 spotted appearance which it occasions on them. It is by means of 

 these also that it teases u's in the heat of summer, when it alights 

 on the hand or face, to sip the perspiration as it exudes from and is 

 condensed upon the skin. The fluid ascends the proboscis, partly by 

 a sucking action, assisted by the muscles of the lips themselves, which 

 are of a spiral form, arranged around a highly elastic, tendinous, and 

 ligamentous structure, with other retractile additions for rapidity and 

 facility of motion."* The beautiful form of the spiral will be best 

 seen under a magnifying power of 250 diameters, or quarter-inch 

 object-glass. 



These insects are of great service in the economy of nature, their 

 province being the consumption of decaying animal matter, given out 

 in such small quantities, that they are not perceptible to common 

 observers, neither removable by the ordinary means of cleanliness, 

 even in the best-kept apartments, in hot weather. It was asserted by 

 Linnseus, that three of these flies would consume a dead horse as 

 quickly as a lion. This was, of course, said with reference to the 

 offspring of such three flies ; and it is possible the assertion may be 

 correct, since the young begin to eat as soon as they are born. A 

 single blow-fly has been known to produce twenty thousand living 

 maggots ; and each of these continues eating so voraciously, that in 

 twenty-four hours it has increased its own weight above two hundred 



* Mr. G. Newport, Cyclopedia of Anatomy and Physiology* 



