OF NATURAL HISTORY. 17 



Many infeds are dcflitute of particular organs. Some want eyes, 

 ears, brain, and noftrils. Other have an acute fenfe of fmelling, 

 though we know not the form or fituation of the organ. The in- 

 ferior fpecies of infeds have no internal lungs, but receive air by 

 lateral pores, and fometimes by long tubes, or tracheae, which pro- 

 trude from different parts of the body. Many infeds have nO' 

 heart, or general refervoir for the reception and propulfion of the 

 blood. But we dlfcover by the microfcope, that their blood circu- 

 lates by the pulfation of arteries, and that their different fluids are 

 fecreted by glands. In a word. Nature, in the flrudlure and func- 

 tions of animals, defcends, by degrees alinofl: imperceptible, from 

 man to the polypus, a being which, ever fmce its oeconomy and 

 properties were difcovered by M. Trembley, has continued to aflo- 

 nifti both philofophers and naturalifts. The flrudure of the poly- 

 pus, which inhabits frefh water pools and ditches, is extremely 

 fimple. Its body confifts of a fingle tube:, with long, tentacula, or 

 arms, at one extremity, by which it feizes fmall worms, and con- 

 veys them to its mouth. It has no proper head, heart, ftomach, or 

 inteftines of any kind. This fimplicity of ftradure gives rife to an 

 equal fimplicity in the oeconomy and fundions of the animal. 

 The polypus, though it has not the diftindtion of fex, is extremely 

 prolific. When about to multiply, a fmall protuberance or bud ap- 

 pears on the furface of its body. This bud gradually fwells and ex- 

 tends. It includes not a young polypus, but is the real animal in 

 miniature, united to the mother as a fucker to the parent-tree. 

 The food taken by the mother pafTes into the young by means of a 

 communicating apeiture. When the fliooting polypus has acquired 

 a certain growth, this aperture gradually clofes, and the young 

 drops off, to multiply its fpecies in the fame manner. As every 

 part of a polypus is capable of fending off flioots, it often hap- 

 pens, that the young, before parting from the mother, begin to 

 Ihoot; and the parent-animal carries feveral generations on her own 

 1 G. body,. 



