S44 
'H EllINTflOlOGT, 
grain of font! to the ibyMc of an orange; commonly 
called hydatids: the other long and flat, and much re- 
fembling a piece of .tape, whence it derived its popular 
name. Both kinds are oviparous., and aftonilhingly pro- 
lific ; though in.other circumftances they differ exceed¬ 
ingly, not oql.y in ftiape., fize, and form, but in their 
deflination in the animal frame. 
The ftmCture of the tapeworm is extremely curious ; 
but what furprifes moft is its incredible length. Many 
have been voided in England from' fifteen to thirty feet 
Jong ; but fome are faid to megfure fixtyfeet, and Boer- 
haave exprefsly mentions his having met with one no 
Jefs than thirty ells in length. There appear to be 
•three fpecies of this worm incident toman : the tcenia 
folium, laid to be endemic in Great Britain, Saxony, and 
Holland ; the tania vulgaris, in Sweden ; and the tcenia 
lata, in Swifler'land and RutTia. This fingularity, per¬ 
haps, may not be ftriCtly founded.; but from the obfer- 
■■vations of different naturalifts and phyficians., as far as 
experience can warrant,, the fact is generally thus ftated. 
The folium derives its name from the fuppolition, that 
there never is but ,o'nc of this fpecies inhabiting at the 
fame time in the fame individual ; whence the French 
call it U ver folitaire. It is however certain that feveral 
of them have been voided by the fame patient in very 
ihort intervals of time, and that they are gregarious. 
“That thefe worms fliould be created for the pur- 
pofe of producing difeafe in the animal which they in¬ 
habit, is abfurd ; it would rather Teem, (fays Mr. Car- 
iifie, Linn. Tranf. vol. ii. p. 248,) that nature has not 
intended any fituation to be vacant, where it was pofli- 
.ble to multiply the fcale of living beings.” Perhaps, 
therefore, a certain .proportion of thefe animals may be 
conducive to health, juft as a certain proportion of dif¬ 
ferent fluids is fo ; vvhilft an exceflive increafe always 
produces difeafe. It is however not to be doubted but 
that worms, and efpecially the taenia, do fometimes pro¬ 
duce difeafed flates of the bodies which-they inhabit ; 
though we are alfo well allured that worms do ex ill 
abundantly in many animals without at all diftiubing 
their funCtipns, or giving them the fmalleft annoyance. 
It fliould alfo be confidered tliat many flates of the ani¬ 
mal body are highly favourable to the increafe of worms ; 
as dropfy to that of hydatids, and the rot in fbee.p to 
that of the Fafciola hep.atica or gourd-worm. 
The taEnia folium is very correctly defcribed by Dr. 
Hooper, in the fifth volume of the Mem . Med. Soc. Land. 
1779, as follows : The head is placed at the fmalleft ex¬ 
tremity of the worm, and united to a chain of articula¬ 
tions more or fiefs broad or long, which gradually en¬ 
large as they advance, and at length terminate in the 
tail, formed by a rounded joint. Each of thefe joints 
contain their proper vifeera. When viewed by the 
naked eye, and lying upon a flat furface, three projec¬ 
tions prefent themfelves, one anterior, and the others 
lateral. But if the head be held up, and its extremity 
viewed attentively, five projections .are confpicuous ; 
one fitnated directly anteriorly and in the middle, and 
the other four backwards, and laterally. The anterior 
projection is the prohofeis of the worm. When exam¬ 
ined by the aid of giafles, it prefents a protuberant mar¬ 
gin, fuirounding an excavation of a ftriated appearance 
like a ftar. In the centre of this is an orifice or mouth 
leading to the alimentary canal. The ftellftted appear-; 
ence,. when more , minutely examined and enlarged by 
the magnifying lens, is found to be compofed of two Te- 
ries of radii, with little bulbs or veficles correfponding 
to the -number of fibrils, with which the margin is be- 
fet, and whidfi gives it a laciniated appearance. Thefe 
lacinice are (aid to be vaginal, including fu&etrial bulbs, 
whence they have named them vagina Jugentes. 
Faffing- backwards we come to the neck of the pro- 
•boftis, v. Inch, as it advances towards its bafts, becomes 
flattened and broader. Its bafts is-quadrangular, and 
has a hollow protruding tubercle-or ofoulum at each 
angle. It then becomes .confide* afoly (flattened, and 
forms a thick margin, which receives the fuperioror 
adjacent margin iof the next joint. In this fpecies of 
.taenia ithe joints differ very much in the-.fame worm. 
They are, for the moft part, oval, rhoraboidal, oblong, 
or quadrangular, and .generally have a great refemblance 
to large cucumber-feeds. They are ftiorteft near .the 
head, and their .length towards the tail is fometimes ex¬ 
ceeded by their breadth. .When the furface of a joint 
is viewed b.y a- micr.ofcope, ire Sly iafter it has been 
wiped witlt a fponge, it appears rough and villous ; but 
it foon becomes covered with a white'tenaceous liquid,, 
which exudes through the pores of the (kin. If this 
liquid be again-wiped oft during the life of the animal, 
fit is quickly renewed. On the margin of each joint, 
-near the middle, sis an ofoulum, and none >o.n the op- 
.pofite margin ,of the fame joint. It (fometimes hap¬ 
pens.that a joint.is f.urnifhed with more than one ofeu- 
fium. They iliave frequently been obferved with three 
or four. But, in general, the next joint has its ofoulum 
fitnated on the margin of the oppofite fide, fo that it al¬ 
ternately changes. This order, howe ver, isfeldom.pi.e- 
-ferved throughout the whole traS of the worm, for they 
are fometimes on the fame fide for feveral joints toge¬ 
ther, but they never are fitnated cn the flattened, fur¬ 
face ; hence their being marginal is an e(fejitia 1 charac¬ 
ter.of the taenia folium.—^See Helminthology Plate I. 
-fig. 1. 
There appears to be but one membrane in'the taenia, 
which is very porous and elaftic, .and which feems, from 
fome experiments, to'be endowed with nervous power. 
Taeniae, therefore, have no Cuticle. The head is made 
up, like the other parts of the worm, of cutis and muf- 
cjular fibres. The fibres, however, are not in any regu¬ 
lar order, .but appear to run in every direction, and are 
united together by a connecting cellular membrane. 
The head contains alfo within it the beginning of the 
alimentary canal, which originates, from the mouth by 
a Ample tube or cefophagus, that bifurcates near the 
bafts of the probofeis. This bifurcated alimentary tube 
proceeds from the. head near each margin of the worm 
to the other extremity. Through this canal the animal 
conveys the food to every part for its growth and in¬ 
creafe. . 
When the cutis is removed, the mufcles of the worm 
are laid bare. They are of a white colour, very much 
.refemble the coagulable lymph, and are difpofed into 
two orders, evident to the naked eye. 1. The longitu¬ 
dinal or external mufcles, which are of a ftrong firm 
texture, running parallel to each other in the direction 
of. the worm, being firmly attached to a kind of liga¬ 
mentous band, and placed along the articulatory re¬ 
ceiving margin of each joint. 2. The tranfverfe mufcles, 
which are fitnated under the longitudinal, and acrofs 
the joint tranfverfely from one extremity to the other. 
When the longitudinal mufcles contraCt, the length of 
thejoint is diminithed and drawn forward. The tranf¬ 
verfe mufcles aCt by diminiftiing the breadth of the 
joint,, and fometimes render it almoft round. Each ar¬ 
ticulation, or joint, is furniflied internally with two dif- 
tinft kinds of veflels, the alimentary tube, and the ova- 
ria. The reft of the joint is compofed of a connecting 
cellular fubltance. 
The alimentary canal enters the ftruCtureof the head, 
at the . bafts of which it divaricates into two diftinCt 
tubes, which are continued near the margins from one 
extremity to the other, and in the extreme joint, where 
it is impervious, there being.no opening analogous to 
an anus. This longitudinal tube is alio fupplied with 
tranfverfe'canals. There is always one fent. acrofs each 
joint along the articulatory receiving margin to the ca¬ 
nal on the oppoftte fide, with which it has a communi¬ 
cation, fo that the contents of one tube are, with great 
facility, communicated acrofs to the other. 
Each individual joint has.a vafcular ftruCfure fitu- 
ated 
