726 A N I M A 
orbicular fhell, a truncated apex, Four teeth, Fmooth bale, 
and no tail. 3. 'I lie pala, is of a yellow colour ; univalv- 
ed, with an oblong pxcavated fhell ; with four long teeth 
at the apex ; with a fmooth bafe. 4. The pipa'lium, is 
univalved, the fhell oblong, and inflected, ten teeth at the 
apex, the bafe fmooth, and a fpurious tail. 5. The pati¬ 
na. is extremely bright and fplendid, has a large body, a 
criflalline and nearly circular fhell, without either incifion 
or teeth, only towards the apex it falls in fo as to form a 
fmooth notch. A double glittering organ, with ciliated 
edges, projects from the apex ; both of them of a conical 
figure, and Handing as it were upon a pellucid fubfiance, 
which is divided into two lobes, between which and the 
rotatory organ there is a filver-coloured crenulated mem¬ 
brane. 6. The clypeatus, is univalved ; the fhell oblong, 
apex notched, the tail naked, and bafe fmooth. 7. The 
lamellaris, is univalved ; the fhell extending confidently 
beyond the body ; tire bafe divided into three fimall horns, 
with two hairs at the end of the tail. 8. The patella, is 
found in marfhy water in the winter time : it is univalve, 
the fhell oval, plain, cryfialline, with the anterior part ter¬ 
minating in two acute points on both (ides : by thefe points 
it tuftens itfelf, and whirls about the body ereCt : the ro¬ 
tatory cilia are perceived with great difficulty. 9. The 
braBca is univalved, the fhell fomewhat orbicular, apex 
lunated, bafe fmooth, and the tail furnifhed with two 
fpines. 10. The plicatilis, is univalved, with an oblong 
fhell, the apex hairy, and bafe notched. 11. The ovalis 
is bivalved ; the fhell flattened, apex notched, a hollow 
part at the bafe, the tail formed of two tufts of hair. 
12. The tripos is bivalved, the apex of the fhell beardlefs, 
three horns at the bafe, and double tail : it fixes itfelf to 
objects by the filaments of the tail. 13. The dentatus, is 
bivalved, with an arched fhell ; the apex and bafe are 
both toothed, and the tail formed of two fpines. 14. The 
mveronatus, is bivalved, fomewhat of a fquare form ; the 
bafe and apex pointed ; the tail confifting of two fpines. 
15. The uncinatus, is one of the fmalleft bivalved animal¬ 
cules ; the apex and anterior part round, the hinder part 
firaight, terminating in a point, furnifhed with a hook on 
the fore part, a fmall rotatory organ, a long tail compofed 
of joints, arid divided at the end into two briftles. 16. 
The cirratvs, is larger than the preceding ; ventricofe, 
fomewhat tranfparent, the head conical, with a bundle of 
hairs on both fides ; it has likewife a rotatory organ. 17. 
The pajfus, has a cylindric fhell, with two long pendulous 
locks of hair proceeding from the front, the tail confifting 
of a Angle bridle. 18. The quadratus, has a quadrangu¬ 
lar fhell, with two fmall teeth at the apex, two horns 
proceeding from the bafe, and no tail. 59. Theimpref- 
fus has a quadrangular fhell, a fmooth undivided apex ; 
obtufe bafe ; notched margin ; and flexuous tail. 20. The 
brachionus Bakeri, has a ventricofe fhell, four teeth at the 
apex, two horns at the bafe, and a long tail terminating 
in two fhort points. Mr. Muller has alfo difeovered in this 
creature two fmall feelers, and a tongue. 21. Th e patu- 
ius, has a ventricofe fhell, with eight teeth at the apex ; 
the bafe lunated, or hollowed into the form of a crefcent, 
and furnifhed with four horns; the tail fhort, with two 
fmall points at the end. 
Thefe are the different kinds of animalcules which have 
yet been difeovered, and to which we fhall add the follow¬ 
ing obfervations by Mr. Adams.—“ How many kinds of 
thefe invifibles there may be (fays he) is yet unknown ; as 
they are difeerned of all fizes, from thofe which are barely 
invifible to the naked eye, to fuch as refifl the force of the 
microfcope as the fixed ftars do that of the telefcope, and 
with the greateft powers hitherto invented appear only as 
fo many moving points. The finalleff living creatures 
our inftruments can fnew, are thofe which inhabit the wa¬ 
ters ; for though animalcula equally minute may fly in the 
air, or creep upon the earth, it is fcarcely poffible to get a 
view of them ; but, as water is tranfparent, by confining 
the creatures within it we can eafily obferve them by ap¬ 
plying a drop of it to the glades, 
L C U L E. 
“ Animalcules in general are obferved to move in all 
directions with equal eafeand rapidity, fometimes oblique¬ 
ly, fome times firaight forward ; fometimes moving in a 
circular direction, or rolling, upon one another, runnino- 
backwards and forwards through the whole extent of the 
drop, as if diverting themfelves ; at other times greedily 
attacking the little parcels of matter they meet with. Not- 
withfianding their extreme minutenefs, they know how to 
avoid obftacles, or to prevent any interference with one 
another in their motions : fometimes they will fuddenly 
change the direClion in which they move, and take an op- 
pofite one ; and, by inclining the glafs on which the drop 
of water is, as it can be made to move in any direClion, fo 
the animalcules appear to move as eafily againft the ftream 
as with it. When the water begins to evaporate, they flock 
towards the place where the fluid is, and fhew a great 
anxiety and uncommon agitation of the organs with which 
they draw in the water. Thefe motions grow languid as 
the water fails, and at laft ceafe altogether, without a pof- 
fibility of renewal if they be left dry for a fhort time. 
They fufiain a great degree of cold as well as infects, and 
will perifh in much the fame degree of heat that deftroys in¬ 
fects. Some animalcules are produced in water at the freez¬ 
ing point, and fome infeCts live in fnovv. By mixing the leaft 
drop of urine with the water in which they fwim, they in- 
ftantly fall into convulfions and die. The fame rule feerns 
to hold good in thofe minute creatures which is obferva- 
ble in the larger animals, viz. that the larger kinds are lefs 
numerous than fuch as are fmaller, whilfi tire fmalleft of all 
are found in fuch multitudes, that there feems to be my¬ 
riads for one of the others. They increafe in fize, like 
other animals, from their birth until they have attained 
their full growth; and, when deprived of proper nourifk- 
ment, they in like manner grow thin and perifh.” 
The modes of propagation among thefe animalcules are 
various, and the obfervation of them is extremely curious. 
Some multiply by a tranfverfe divifion ; and it is remark¬ 
able, that, though in general they avoid one another, it 
is not uncommon, when one is nearly divided, to fee ano¬ 
ther pufli itfelf upon the fmall neck which joins the two 
bodies in order to accelerate the feparation.—Others, when 
about to multiply, fix themfelves to the bottom of the wa¬ 
ter ; then becoming firft oblong, and afterwards round, 
turn rapidly as on a centre, but perpetually varying the 
direction of their rotatory motion, in a little time, two 
lines forming a crofs are perceived ; after which the fphe- 
rule divides into four, which grow, and are again divided 
as before. A third kind multiply by a longitudinal divi¬ 
fion, which in fome begins in the fore-part, in others in 
the hind-part; and from others a fmall fragment detaches 
itfelf, which in a fhort time affumes the fhape of the pa¬ 
rent animalcule. Laftly, others propagate in the fame 
manner as the more perfect animals. 
Many doubts have been fuggefted, whether all thofe 
minute bodies which go under the name of animalcules , 
really do enjoy animal life ; or whether they are not in 
many cafes to be accounted only inanimate and exceeding¬ 
ly minute points of matter aCtuated by the internal mo¬ 
tion of the fluid. But to all hypothefes of this kind Mr. 
Adams makes the following reply : “ From what has 
been faid, it clearly appears, that their motions are not 
purely mechanical, but are produced by an internal fpon- 
taneous principle ; and that they muft therefore be placed 
among the clafs of living animals, for they polfefs the 
ftrongeft marks and the mod decided characters of anima¬ 
tion; and, eonfequently, that there is no foundation for 
the fuppofition of a chaotic and neutral kingdom, which 
can only have derived its origin from a very tranflent and 
fuperficial view of thefe animalcules. It may alfo be fur¬ 
ther obferved, that as we fee that the motions of the 
limbs, &c. of the larger animals, are produced by the me¬ 
chanical conftruCtion of the body, and the aCtion of the 
foul thereon, and are forced by the ocular demonftration 
which arifes from anatomical difleCtion to acknowledge 
this mechanifm which is adapted to produce the various 
motions 
