332 



FOOD OF INSECTS. 



tubular tongue, more or less long, sometimes not shorter than 

 three inches, but spirally convoluted when at rest, like the 

 mainspring of a watch, into a convenient compass. This 

 tongue, which they have the power of instantly unrolling, 

 they dart into the bottom of a flower, and, as through a si- 

 phon, draw up a supply of the delicious nectar on v/hich they 

 feed. A letter would scarcely suflace for describing fully 

 the admirable structure of this organ. I must content my- 

 self, therefore, with here briefly observing that it is of a carti- 

 laginous substance, and apparently composed of a series of 

 innumerable rings, which, to be capable of such rapid con- 

 volution, must be moved by an equal number of distinct 

 muscles; and that, though seemingly simple, it is in fact 

 composed of three distinct tubes — the two lateral ones cy- 

 lindrical and entire, intended, as Keaumur thinks, for the 

 reception of air, and the intermediate one, through which 

 alone the honey is conveyed, nearly square, and formed of 

 two separate grooves projecting from the lateral tubes ; which 

 grooves, by means of a most curious apparatus of hooks like 

 those in the laminae of a feather, inosculate into each other, 

 and can be either united into an air-tight canal, or be instantly 

 separated, at the pleasure of the insect. ^ 



Another numerous race, the whole of the order Hemiptera, 

 abstract the juices of plants or of animals by means of an in- 

 strument of a construction altogether different — a hollow 

 grooved beak, often jointed, and containing four bristle- 

 formed lancets, which, at the same time that they pierce the 

 food, apply to each other so accurately as to form one air- 

 tight tube, through which the little animals suck up^ their 

 repast; thus forming a pump, which, more eflective than 

 ours, digs the well from which it draws thje fluid. 



A third description of insects, those of the order Diptera, 

 comprising the whole tribe of flies, have a sucker formed on 



1 For a full description of this Instrument, see Reaum. i. 125, &c. 



2 The mode, however, In which this is effected, in all insects furnished with a 

 proboscis, can scarcely be by suction, strictly so called, or the abstraction of air, 

 since the air-vessels of insects do not communicate with their mouths : it is more 

 probably performed in part by capillary attraction ; and, as Lamarck has sug- 

 gested {Syst. des Anhn. sans Vertebres, p. 193.), in part by a succession of undu- 

 lations and contractions of the sides of the organ. 



