INJECTION. 
The fubjeft muft be laid upon a table of fufficient 
height, which might be contrived with a ledge fixed to 
the table in fuch a manner as to be water-proof; which 
would be ufeful for preventing the quickfilver, which is 
alrnoft always neceffary for injecting thefe veffels, from 
being loft. The fnrface of the table ftiould likewife be 
hollowed, fo that the mercury which falls may be colleft- 
ed in the middle, where a hole with a ftoppet may be 
made to take out occafionally the quickfilver which col- 
lefts. Such a table would alfo be convenient for holding 
water for the purpofe of fteeping membranous parts which 
are frequently to be injefted ; and which, from being ex- 
pofed to the air, become dry ; which alfo it is inconve¬ 
nient and hazardous to move into water during the time 
of operation. Even a common -table with a hole cut in 
the middle may anfwer the purpole; the hole may be 
round or fauare according to the fancy of the anatomift ; 
but the table muft be conftrufted of fuch materials as are 
not liable to warp in warm water. Should the anatomift 
not be provided with either of thefe tables, the parts 
muft be laid in a tray or earthen dilh, that the quickfilver 
may be faved. 
The materials for injefting thefe veffels are only quick- 
filver, and the ceraceous or coarfe injeftion of anatomifts; 
the former being always ufed in injefting the lymphatics 
and lafteals, it being alrnoft impoflible to fill them with 
another fluid in the dead body. The ceraceous injeftion 
is chiefly ufed for the thoracic duft.; and in fome parti¬ 
cular inftances, where the lymphatic trunks have been 
found larger than the ordinary fize, a coarfe injeftion has 
been made ufe of. 
l'njeftions of the lymphatics may be made even while 
the animal is alive, and that without any great cruelty, 
by feeding it with milk previous to its being ftrangled. 
Of all the barbarous methods of opening the animal while 
alive, the moft ufeful feems to be that of Mr. Hunter, who 
direfts to perforate the fmall inteftines, and throw in 
ftarch-water with folutions of mutk, or indigo and ftarch- 
water. -“In a word, (fays Mr. Sheldon,) any gelatinous 
fluids, rendered opaque with fuch colours as will be ab- 
forbed, are extremely ufeful for experiments of this kind ; 
for much more may be feen by examining the veflels dif- 
tended with a coloured fluid from natural abforption, than 
by anatomical injeftion praftifed in the dead body.” Lie- 
berkuhn firft difcovered the ampuilulte by feeding chil¬ 
dren in whom the lafteal glands were obftrufted previous 
to their death with milk; by which qteans not only the 
lafteal trunks became diftended with chyle, but likewdfe 
the ampullulce. Thus the abforbing mouths of the lac¬ 
teal veflels were difcovered by Lieberkuhn ; and in a fimi- 
lar manner Afellius difcovered the lafteals themlelves. 
Thus alfo Euftachius difcovered the thoracic duft in a 
horfej and Mr. Hewfon traced the lafteal veffels, lympha¬ 
tics, and thoracic duft, in birds, by making ligatures on 
the root of the rneferitery, and other parts, which had 
been previoufiy fed with barley. Mr. Hunter likewife 
was enabled to obferve the lafteals of a crocodile when 
diftended with chyle. 
The coarfe injeftion for the lymphatics is made of mut- 
ton-fuet and yellow refin, in the proportion of two-thirds 
of refin to one of fuet. If required of a thicker conflu¬ 
ence, we may add a fmall quantity of pure wax; if of a 
fofter quality, we may augment the quantity of fuet. Or- 
piment, or king’s yellow, is generally made ufe of; though 
others are equally proper, provided they be fine enough. 
The inftruments neceffary for injefting the lymphatic 
veffels are the injefting tube and pipes, lancets, blow¬ 
pipes, knives, fciffars, forceps, needles, and thread. The 
old injefting-tube has been found in a manner entirely 
ufelefs, the pipe being fixed in a glafs tube two or three 
feet long; which is one of the reafons why, before the 
time of Hewfon, fo little of the’ lymphatic fyftem could 
be injefted. Tubes of fuch a length are entirely unma¬ 
nageable by one perfon, and it is impoflible to perforin 
the operation properly with two. To perform it in the 
beft manner, the inftrument ihouid be held in the hand 
like a pencil or pen. The inftruments ufed by our au¬ 
thor, are tubes made either of glafs or of brafs; which, 
when filled with mercury, may be held in the hand like 
a pen ; a glafs tube, however, is preferable to the metal¬ 
lic one. It is fomewhat in the'Inape of a trumpet; fix 
inches and a half in length, an inch and a half broad 
where broad eft, and three-eighths of an inch where nar- 
roweft. A collar of fteel half an inch broad and three 
quarters of an inch long is cemented to this pipe, and a 
fmaller tube of the fame metal is fcrewed upon the end of 
the collar; the whole terminating in a capillary tube 
about an inch in length. This laft is the moft difficult 
part of the whole work to execute; it ftiould be drilled 
out of a folid piece of metal, and not made of a thin bit 
of plate foldered, as thefe are apt to turn ragged in the 
edges, and the folder is alfo liable to be deftroyed by the 
mercury. Thole ufed by Mr. Sheldon were made by dril¬ 
ling a fmall hole lengthwife through a bit of well-tempered 
wire. It is cleaned by means of a very fmall piece of 
fteel-wire capable of palling through the bore of the tube. 
This ought to be annealed left it ftiould break ; in which 
cafe the broken bit could not eafily be got out. Very 
fmall tubes may be made of glafs drawn out as fine as we 
choofe ; and, though very apt to break, they are eafily re¬ 
paired. They ought to be very thin, that they may be 
eafily melted. Sometimes it lias been found convenient 
to fit the collar with a fteel ftop-cock. The brafs tube 
reprefented by our author is about nine inches and a half 
in length, and half an inch wide where wideft. The collar 
is a full quarter of an inch broad, and three quarters of an 
inch long; a fteel piece and capillary tube being fcrewed 
to it as in the other. The lancets are to be exquifitely 
fliarp, in order to cut into the lymphatic veffels. The 
latter are eafily inflated by the fmall filver blow-pipes ufu- 
ally put up in the diffefting-cafes by the London mathe¬ 
matical inftrument makers; diffefting-knives,fine-pointed 
fciflars, accurately-made diffefting-forceps, with ftraight 
or crooked needles, are likewife fubftituted with advan¬ 
tage, as not being affefted by the quickfilver. 
We muft next eonfider the proper fubjefts for injec¬ 
tion. Mr. Sheldon recommends, that they fliouid be as 
free from fat as poffible ; he has always found in the hu¬ 
man fubjeft thole who died univerfally dropfical, or of an 
afcites or anafarca, to be the beft, for the following rea¬ 
fons, viz. in fuch there is little or no animal oil, and but 
a very fmall quantity of red blood; both of which, when 
they occur in great abundance, very much impede the 
difcovery of the lymphatic veflels ; but, when the cellu¬ 
lar Veffels are loaded with water, the abforbents are more 
readily traced, and with lefs ri(k of wounding them in 
diffeftion f the preparations alfo, particularly the dried 
ones, are more Jailing. This circumftance is found to be 
of moft confequence in preparing the abforbent veffels of 
the trunk and extremities of the human fubjeft. Of all 
the vifcera in young fubjefts, only the liver and lungs 
can be injefted with fuccefs ; und thefe may be fuccels- 
fnlly injefted even in the foetus. It will be moft proper 
to begin the operation upon the fubjeft immediately after 
death, as lymph or chyle will then be more readily found 
in the veffels, than when we wait a longer time. In 
preparing the lafteals, previoufiy diftended with milk in 
the living fubjeft, it is proper to have the inteftines and 
mefentery plunged (with the ligature upon the root of 
the latter) into reftified fpirit of wine. This procefs will 
coagulate the chyle; and, the fluid being opaque, the 
veflels will be beautifully leen when we mean to prepare 
the parts, by preferving’ them in proof-fpirit, as wet fpe- 
cimens : “In this way (fays Mr. Sheldon) I have made 
in the dog one of the moft natural preparations that can 
be feen of the lafteals injefted from their orifices by the 
natural abforption.” We may alfo prepare the lafteals 
by the method ufed by Mr. Hunter, already mentioned ; 
by which they will be very confpicuous, by the indigo 
abforbed from the cavity of thS inteftines. By tying the 
thoracic 
