II Y D II A. 619 
the ground at the fame time not rendered arable thereby, 
typified by a poifonous ferpent; and was thus exprelfive 
of the rage of peftilential effluvia, which fometimes, and 
under certain circumftances, continue in a virulent Itate 
in dry weather, near their dried fources.. 
Hydra is feemingly mentioned by Virgil (zEn. vi. v. 
576.) as a fictitious or poetical animal. Bochart, how¬ 
ever, with his ufual erudition, appears defirous to make 
the whole llory literally intelligible. (Hierozoici pars 
poller, lib iii. cap. xili.) But Lancifi, with a more clear 
and difcriminating mind, perceives that important phyfi- 
cal truths are concealed under this two-fold allegory, and 
ihows how they are to be unriddled. (De Nox. Palud. 
Effl. lib. ii. p. ii. cap. 3.) Many of the claflical writers, 
and others-, life the word “ hydras,” as well as “ hydra,” 
and fome of them apparently confound the two. 
It may here be not incurious to ftate the hiltory of this 
fabulous nronfter, as recorded in Seba’s Thefaurus, from 
which celebrated work the following tranflation is given. 
«The drawing of this creature, called the feven-headed 
hydra- was prefented to Seba by a foreign nobleman, who 
went to vifit his cabinet of curiofities in the year 1720. 
He affirmed that he had frequently feen the original at 
Hamburgh; that the drawing refembled the living hydra ; 
that it had feven ere6t heads, and the lame number of 
wide gaping jaws, armed with long and fhort hooked teeth. 
I cor.fefs, fays Seba, that this account appeared to me pa¬ 
radoxical, and bordering more upon the marvellous than 
the truth. But in the following year, D. H. Eibfen, the 
minifter of Dingen, in a part of the duchy of Bremen 
called Wurffen, came to fee me for the fake of infpefting 
my tnufeum, who likewife, relating to me a fimilar ac¬ 
count of this hydra, promifed that he would fend me a 
figure of it drawn from life, as it was then at Hamburgh; 
and as he was acquainted with Degern and Hambel, mer¬ 
chants at Hamburgh,who were the pofl'effors of it, he llrould 
have a moll excellent opportunity of performing his pro- 
mife. This lingular animal was firft in poffeffion of the fa¬ 
mous count van Koningfmarck ; upon his death it went 
by will to his relation the count van Leeuwenhaupt. I had 
heard that it was upon fiale; and upon enquiry, I was in¬ 
formed that ten thoufand florins was the price alked for it, 
which vaft fum made me the more defirous of having an ex- 
aft reprefenration of it. D. Eibfen made good his word, by 
fending me the much-wilhed-for drawing, but, not being 
perfectly fatisfied even with this, I wrote upon the fubjeft 
to my triend John Frederic Natorp, at Hamburgh, a very 
great naturalill, who himfelf had feen the thing in quel'- 
tion, and allured me that it was the produce of nature, 
not of art ; and he, at my requelt, lent me a coloured 
drawing of it, in its natural form, from which the an¬ 
nexed engraving was taken. The colour is dulkiftubrown, 
as it were (haded with a cinereous grey. The back is 
warted ; on each fide are fix horny oblong warts ; under 
thefe on the tides next the belly are feven other round 
horny knots, or knobs, extending from the feet to the tail. 
The whole body and (even heads are of a deepilh browm ; 
the Ikiii is not covered with fcales, but variegated like 
marble. The front of the necks are encircled, as it were, 
with tranfverfe belts. All the feven mouths are equally 
open, armed with teeth, like thofe of the lion. The whole 
of the tail, which is very long, is encafed with rhom- 
boidai fcales. Each foot is cleft into four parts, ex¬ 
tending the toes, which are armed with long and lharp 
claws. 
“ If upon this occafion, (Seba adds,) I fliould be defi¬ 
rous of examining into what antiquity has furnilhed us 
with upon the fubjeft of hydras and dragons, generally 
claffed by it among the larger l’erpents, I fear I Ihould 
tire the reader, becaul'e it abounds in jitlions of this kind. 
Conrad Gefner, in his Hill. An. lib. iv. p. 459, gives a 
plate of a hydra by him called monjlrous, or a leven-headed 
lerpent; the heads like thofe of lions, and as it were or¬ 
namented with crowns; two feet in the front of the body ; 
the tail twilled inwards: of which creature he relates, 
that in the year 1530 this molt hideous feven-headed aqua¬ 
tic ferpent was brought from Turkey to Venice; that it 
was there expofed to public view, and afterwards fent to 
the king of France, and valued at fix thoufand ducats. 
A circumllance which appeared incredible to naturalifts. 
Aldrovandus likewife, in his book of ferpents, has a plate 
of a feven-headed dragon., Athanafius Kircher, lib. 8. 
de Animal. Subterran. p. 91, gives a reprefentation of a 
dragon of the fame kind, but furnilhed with one head 
only, two horfe’s ears, the mouth filled with teeth, 
the tongue Ihort, two wings like the fins of filh, two feet 
covered with fcales, and having a tail like, the lizard; 
This farrago of fiftion induced profelfor John James 
Scheuchzer to confefs^Jn Jobi Phyfica Sacra, p. 259, that 
with all his endeavours and refearches upon dracontology, 
he had hitherto found nothing at all fatisfaftory; and 
from thence he takes occafion to obferve, with how many 
and great falfities both the world and himfelf h^ve fuffered 
themfelves to be deceived. 
HY'DRA, in allronomy, a fouthern conftellation, con- 
filling of a number of liars, imagined to reprefent a water- 
ferpent. The ftars in the conlleliation Hydra, in Ptolomy’s 
catalogue, are 27 ; in Tycho’s, 19 ; in Hevelitis’s, 31 ; 
and in the Britannic catalogue, 60. 
HY'DRA, /. [from its putting out fo many heads.] 
The Polype ; in helminthology, a genus of worms be¬ 
longing to the order of zoophyta, the charafters of which 
are : Animal fixing itfelf by the bale, linear, gelatinous, 
naked, contraftile, and furnilhed with fetaceous tentacula 
or feelers, inhabiting frelh waters, and producing its de¬ 
ciduous offspring from the hides. 
The body confills of a fingle tube, furnilhed at one 
end with long arms ; by thefe it feizes fmail worms, and 
conveys them to its mouth. It has, according to our ge¬ 
neral notions, neither head, heart, llomach, nor intellines, 
of any kind; and is without the diftinftion of fexes, yet 
extremely prolific. From the fimplicity of its ftrufture 
thofe of its oeconomy and funftions are probably derived. 
When they are cut or divided into a number of pieces, 
the feparated parts in a very little time become fo many 
perfeft and diltinft animals ; each piece having a power 
of producing a head, a tail, and the other organs necef- 
fary for its exillence. They are generally known by the- 
name of polype ; but, as this was thought by many to be 
improper, becaufe that, llriftly lptaking, they have no 
feet, Linnseus called the genus hydra , probably from their 
property of reproducing the parts which are cutoff, a cir¬ 
cumllance that naturally brings to mind the fabulous llory 
of the Lernean hydra. Dr. Hill called them biota, on ac¬ 
count of the llrong principle of life with which every part 
is endued. 
Leeuwenhoeck, whofe indefatigable indullry in his re¬ 
fearches after fmail infefts permitted very few things to 
efcape his notice, difcovered thefe animals, and gave lome 
account of them in the Pbilofophical Tranfaftions for the 
year 1703. There is alfo in the fame volume a letter 
from an anonymous hand on this fubjeft. We had, 
however, no regular account of them, their various ha¬ 
bits, their different fpecies, or of their wonderful proper¬ 
ties, till the year 1740, when they firft engaged the atten¬ 
tion of M. Trembley, to whofe affiduity and obfervations 
we are indebted for the difplay of their nature and oeco¬ 
nomy. Previous to the luccefsful experiments of this 
gentleman, Leibnitz and Boerhaave, as well as lome of 
the ancient philofophers, reflefting on the various grada¬ 
tions in the fcale of animated nature, had endeavoured to 
prove that there might be degrees of life between the 
animal and the plant, and that animals might be found 
which would propagate by Hips, like plants. Thefe con¬ 
jectures were verified by Trembley, but not in confe- 
quence of any pre-conceived ideas in favour of fuch a 
fuppofition ; on the contrary, it was only by repeated 
obfervations that lie could deltroy his own prejudices, 
and join thefe wonderful beings to the animal kingdom. 
Thus, we find M. Trembley writing in January 1741, to 
M.' Bonnet, that he did not know whether he Ihould call 
the objeft which then engaged his attention a plant or an 
animal; 
