^4 Obfervations 9n the Ipoma^a H'tj'plda. 



be cut off, it continues to fly about, to \valk, to leap, and \o, 

 climb as before; its regular and uniform motions, fomeliniei 

 flow and tranquil, fonieiimes quick and animated, exhibit 

 nothing convulfive, nothine; that refembles thofe violent agi- 

 tations which aecompauv pain. In a word, the number and 

 rapidity of thefe movements, as well as the time that thefe 

 flies can live, are fubjeci to no fixed rule. 



Let us (lop for a moment to confider the movement of 

 their legs; they are equally various and wonderful as thofe 

 by which they can move the whole of their body. 



XXV. To appreciate properly the ditVerent'ni'n'ements per- 

 formed by an animal in a ft;ite of health or of dileafe, it is 

 necedarv to have an exciA idea of the circumftances in which 

 it is placed, of the motives and inipulfes which in general 

 induce it to move; in a word, we mull be acquainted with 

 its nature and chanu^er. This being preinifed, it is eafy to 

 obferve, that of the nine kinds of nu)vement to which thofe 

 executed by flies in a ftate of health may be reduced, eigh^ 

 ftill fuhfifl even after they have been deprived of the head. 

 Scarcely has a fly been decapitated when it is feen to move 

 its hind legs for a long time, and at ditTcrent periods to crols 

 ihem, either ftanding up or fivinar, to rub them along its body, 

 to hook the one into the other in the form of a wheel, and 

 to agitate them in a thoufand ways with wonderful rapidity 

 and regularity. All thefe movements, which conltitute the 

 firft kind here treated of, are ablolutelv {]m,ilar to thofe per- 

 formed by a fly, when, poH'ediiig perfect health, and being 

 haralled by no fear or want, it appears to move only for its, 

 own pleafare. Thefe movements, then, feem to be produced 

 in thefe two ftatcs, fo oppofite, by the fame principle^, that is, 

 fenfation and volition. 



XX Vi. The fecond kind of movement refults from their 

 hind legs, which they raife up towards the interior edge of their 

 wings; fo tlial by thefe means they are elevated, and placed 

 in dirte|(nit dire<:tions. The object of thefe movements, ex- 

 ceedingly varied, though conflant, feems to be, to rub, beat, 

 and poiiib their wings. Their hind legs can execute a third 

 kind of movement, no lefs varied, when, conveying them 

 above their wings, which they keep extended, they rub 

 xhem, beat them, and polifli them, as in the preceding cafe. 

 Their middie legs alfo are often obferved to be twilled around 

 thole behmd, and to rub each other nuitnally ; which forms 

 two new kinds of motion diflbrent from thole we have exa- 

 mined. 



larg; ft aniiTnl; : thelc properties belong ns much to ir.lcrofcopic and infu- 

 fion aiiiiTials. as to the elephant and whale. Nothing is cont&mptible in 

 Uic eyes of the uui,iofophi;i : every ihiu" in aatureis great and wonderful. 



XXVII. 



