MUSCID^, OK FLY-TRIBE. MAGGOTS. 203 



It then contracts the body from a circular to an oblong figure ; 

 the contraction extending in a manner to every part of the body. 

 It now suddenly lets go its hold, and straightens the body, with 

 such violence, that the noise produced by its hooks is very 

 perceptible. The height of the leap is often from twenty to 

 thirty times the length of the body ; exhibiting an energy of 

 motion, which is particularly remarkable in the soft Larva of an 

 Insect. A Viper, if endowed with similar powers, would throw 

 itself nearly a hundred feet from the ground. The learned 

 Swammerdam, who devoted much attention to the anatomy and 

 habits of this creature, observes " Now Wfc the sharpest geniuses, 

 and men of the greatest penetration and learning, judge if a 

 creature, on the fabric of which there plainly appears so much 

 art, order, contrivance, and wisdom, nay, in which is seen the 

 hand itself of the Omniscient God, could possibly be the pro- 

 duction of chance or rottenness." This observation refers to the 

 idea formerly entertained almost universally, that the Maggots, 

 which make their appearance in the midst of decomposing 

 matter, are the results or products of that decomposition. Ex- 

 periments devised for the purpose, however, have clearly shown, 

 that there is here no exception to the general rule ; for that, if 

 the parent Insects be carefully excluded, no maggots will make 

 their appearance in a decomposing mass of any description. 

 Of the voracity of the larvae, and the rapidity with which they 

 undergo their transformations and propagate their kind, some 

 idea may be formed from the estimate of Linnaeus, that three 

 Flesh-flies and their progeny would devour the carcass of a dead 

 Horse more speedily than a Lion would do. If this estimate is 

 at all exaggerated, it is probably not much so. Hence we see 

 the vast importance of these Insects in the economy of Nature ; 

 for they are called into existence just in proportion to the 

 demand for them, the eggs of the parent not being developed, 

 unless they are deposited in a fit situation, so that the number 

 of individuals will not be increased unless there is matter for 

 them to feed on, whilst, on the other hand, the rapidity of the 

 growth and metamorphoses of these Insects is greatly increased, 

 by the warmth that promotes the decomposition of the sub- 

 stances, which they are destined to remove. 



