VERMES. 



The idea, which fome have entertained, that the brain 

 and nerves, the mufcular fyftem, &c. of which no trace 

 can be difcovered in the polypi, neverthelefs exift, but are 

 expanded and as it were melted down into the general mafs 

 of the body, fo that every point is capable of fenfation, 

 mufcular motion, &c. is a perfeAly gratuitous and impro- 

 bable fuppofition. On this view, it would follow that a 

 frefh-water polype (hydra) has all the organs of a perfeft 

 animal in every part of its body, and confequently fees, 

 hears, fmells, &c. at all points. Thus it would be a more 

 perfeft animal than man, as each molecule would be equi- 

 valent, in the complement of its organization and faculties, 

 to an entire individual of the human fpecies. If we allow 

 this to the polype, how can we refufe it to the monas, to 

 vegetables ? The ftudy of nature teaches us in all cafes, that 

 when an organ ceafes to exift, the faculty is no longer 

 found. 



The polypi are very irritable, and are afted on by exter- 

 nal influences. Light attrafts them towards the quarter 

 whence it comes, as it does the branches, flowers, and leaves 

 of plants. No polype purfues its prey ; but when a foreign 

 body touches its tentacula, they ftop and convey it to the 

 mouth ; it is fwallowed without difliinftion, digefted if fuf- 

 ceptible of that procefs, otherwife rejefted. 



Lamarck objefts to the term zoophytes, or animal plants, 

 becaufe thefe are truly animals, and have nothing of vege- 

 table nature. The only relations between polypi and plants 

 are in the fimplicity of their ftrufturc, in the conneftion of 

 feveral polypi with each other, fo as to communicate by their 

 alimentary canal, and form compound animals ; and in the 

 external form of the maffes which thefe united polypi com- 

 pofe, a form which for a long time caufed them to be taken 

 for true vegetables, fmce they are often ramified nearly in 

 the fame manner. Wliether polypi have one or more 

 mouths, we muft always bear in mind that tliey lead to an 

 alimentary cavity, that is, to an organ of digeftion which 

 docs not exift in any vegetable. 



The wheel animal of Spallanzani is a remarkable fpecies 

 of this kind (rotifer redivivus ; vorticella rotatoria, Grael.) 

 It is found in ftagnant water, and in the fand of fewers and 

 tiles. It has a tail, and is forked in front ; each portion 

 bearing a kind of toothed wheel, which can be drawn in at 

 pleafure. Internally an organ is perceptible with a flow and 

 irregular motion, fuppofed to be a ftomacli. 



The name of redivivus was given to this creature from 

 its remarkable property, pointed out by Spallanzani, of re- 

 covering life after being long dried. This refufcitation will 

 take place at the end of fome years ; but Spallanzani fays, 

 that the animal muft be kept in the fand in which it is 

 found. (See his Trafts. ) Baker (on the Microfcopc) 

 makes a fimilar reprefentation with refpeft to the eels of 

 blighted corn. 



The vorticcUas of Cuvier, polypes a bouquet, (Brachio- 

 nus, Blumenbach,) have fmall organs, like fine hairs, coming 

 out of their anterior extremities, turning about rapidly and 

 inceftantly : their nature and ufe are unknown. Some have 

 a tail ; others a thread-like peduncle. The latter are united 

 in an arborefcent manner. They inhabit ftagnant waters, 

 and are fo minute, that a mafs of them appears only as a 

 fpot of film. They multiply by fimple divifion, one of the 

 fmill bodies fplitting, and each half becoming an entire 

 one. 



The botrylli, corini, and criftatellsc, or polypes a plumet 

 of Cuvier, are allied to the latter : they poffefs tentacula or 

 ciliated organs ; and are either fingle or coUefted into arbo- 

 refcent maffes. 



In the frcfli-water polypes (hydra), the organizaliun is 



rather more complicated, and the fize of the animal increafes, 

 fo that It is vifible with the naked eye. They are gelati- 

 nous, femi-tranfparent, and therefore not eafily rccognifed 

 by a perfon unaccuftomed to look for them'. Their body is 

 elongated, fmall at one end, by which it is attached to fome 

 aquatic plant, teftaceous animal, &c. and larger at the other. 

 It confifts of a cavity terminating at the large end by a round 

 orifice, furrounded by long tentacula. The animal indeed 

 may be regarded as a ftomach, provided with inftruments for 

 catching its food : the latter is the ufe of the tentacula. 

 The fubftance of the body appears, under the ftrongeft 

 magnifying powers, a mere jelly, with more opaque portions 

 interfperfed. Blumenbach compares it to boiled fago. 

 They hve on naiades, monocuh, and other fmall aquatic 

 animals, which they feize with their tentacula, and convey 

 into the ftomach, where they are digefted, and from which 

 the refufe is rejedled by the fame opening. 



They perform locomotion, and feem very fenfible to light, 

 although nothing like mufcle or nerve can be difcemed in 

 them. Neither have any vcflels been feen in them : they 

 are faid indeed to receive a tint from the food they take, 

 fo that it muft pafs immediately from the ftomach into the 

 organs. 



The moft furprifing circumftances, however, in thefe ani- 

 mals, are their mode of multiphcation and their extenfive 

 power of reproduftion. They propagate by buds from 

 their own body- If cut into fix or more pieces, each be- 

 comes a perfeft animal : they may be inverted, and the ex- 

 ternal and internal furfaces will be changed and afiume each 

 other's funftions. When they are partially divided in the 

 longitudinal direftion, the feparated parts heal fo as to form 

 two heads or tails, &c. See the article Polype ; alfo, 

 Trembley Mem. pour fervir a I'Hiftoire d'un Genre de 

 Polypes d'Eau douce, &c. ; Leid. 1744, 410. Baker's 

 Natural Hiftory of the Polype ; Lond. 1743, 8vo. Rijfel 

 Hiftorie der Polypen ; in the third volume of his Infeften- 

 beluftigungen. Schaffer Armpolypen in den fiiflen Waf- 

 fern um Regenlburg, 1754, 4to. 



From the frcrti-water polypes, there is an eafy tranfition to 

 the animal of the Weft India iflands defcribed by Ellis, in 

 the Phil. Tranf. vol. Ivii. tab. 19. fig. i, and in his Natural 

 Hiftory of Zoophytes, tab. i. fig. i, under the name of 

 aftinia fociata, or clufter animal flower. It is the zoanthe 

 ii drageons of Cuvier, hydra fociata of Gmelin. It is of a 

 tender flcftiy fubftance, confifting of many diftindl tubukir 

 bodies, each of which fwells above into a fmall bulb : at 

 the top of this bulb is the mouth, furrounded by one or 

 two rows of tentacula, which can be extended or with- 

 drawn at pleafure : in the latter ftate they look like circles 

 of beads. Thefe bodies are connefted below to a firm 

 fleftiy wrinkled tube, fticking fail to the rocks, and fend- 

 ing forth other flefliy tubes, which creep along them in 

 various direftions, and give origin to fimilar bodies rifing 

 up irregularly in groups. Knobs are obferved on the ad- 

 hering tube, from its infinuating itfelf into the inequalities 

 gf the coral rock. When the animal is diftttted lengthwife, 

 a large cavity is expofed, into which a tube opens from the 

 mouth. From this tube eight fmall cords arife, continued 

 to the lower part of the animal, where they feem to be loll 

 in the flefliv bafis. 



The fmall polypi will appear to us more wonderful, and 

 will more powerfully engage our attention, when we find 

 that they produce all thofc marine fubftances, formerly 

 called zoophytes, from a notion that they partook both of 

 the animal and vegetable natures, and including corals, co- 

 rallines, madrepores, millcporcs, fponges, &c. &c. So ac- 

 tive are thefe mimilc creatures in fome parts of the ocean, 

 B z that 



