212 
jections by the veins than by the arteries. 
Every anatomist who has had much experience 
in stew | the "ig ft ON vessels has been in- 
commoded by the injection passing unex- 
tedly into some large vein, and on looking 
‘or the communication, he has found the veins 
from a lymphatic gland conveying the injection 
into one of the nearest large venous trunks. 
This has occurred to me frequently in the 
human subject, where the common iliac veins 
and the cava inferior have received the quick- 
silver from the veins of the neighbouring 
lymphatic glands. I have also seen the same 
occurrence lately in the horse, and have the 
specimen shewing the fact now in my museum, 
It was these veins conveying the imjection from 
the lymphatics into the venous trunks, which 
Lippi mistook for the vasa efferentia of the 
glands, and which induced him to publish his 
work describing many terminations to the 
lymphatic system in mammalia, hitherto un- 
known to anatomists. This error was the more 
excusable, inasmuch as his opinion appeared 
to be confirmed on the investigation being 
pursued by himself and others in the remain- 
ing classes of vertebrate animals, where various 
communications do actually take place between 
the lymphatic trunks and the veins. 
Coloured fluids have been thrown into the ca- 
vity of the pleura and peritoneum in living ani- 
mals for the purpose of bringing the lymphatic 
vessels into view, and of tracing if possible their 
extreme branches after absorption had taken 
place. In this way it is said that minute vessels 
anastomosing with each other, and forming a 
delicate net-work, may be made apparent on the 
surface of the serous membrane, and that the 
trunks of the neighbouring lymphatics may be 
seen filled with the coloured fluid. In post- 
mortem examinations also, the absorbent vessels 
have been observed distended with a fluid of a 
yellow or red colour, where effusions of pus 
or blood had taken place during life. Inall these 
instances we probably first notice the injection 
in the larger lymphatic vessels which are easily 
recognized by their numerous valves, and on 
tracing these back to their commencing branches 
we only discover an intricate net-work of mi- 
nute vessels apparently continuous with each 
other. It is exceedingly difficult to distin- 
guish these from equally small branches of 
artery and vein, filled probably with the same 
coloured injection. You look in vain for the 
channel by which the injection has entered 
these vessels ; no continuity of lymphatic with 
the minute twigs of the other sets of vessels 
can be detected ; no open orifice belonging to 
either can be distinguished. Many anatom- 
ists have endeavoured to fill the commencing 
branches of the lymphatic system by forcing’ 
the injection, thrown into them, in a retrograde 
direction, and in fishes where there are no 
valves, with the effect of shewing very nume- 
rous lymphatic vessels destitute of orifices, but 
‘not so universally distributed as has been 
imagined. 
Fohmann, Breschet, and others have simply 
made a puncture in the tissues, and by forcing 
quicksilver into the wound, have occasionally 
LYMPHATIC AND LACTEAL SYSTEM, 
succeeded in filling a minute net-work of lympha- 
tics. Cruickshank and Hewson employes iga- 
tures to the thoracic duct, to the larger lymph: 
tics, or simply round the limb immediately pre- 
vious or subsequent to the death of the anima 
for the purpose of distending the radicles of th 
system. Taaay: the microscope has been hai 
recourse to by most observers. But the pr 
vailing physiological opinions of the day ha 
more influence than all our anatomical in 
vestigations in determining our notions of th 
mode of origin of the lymphatic vessels. I 
deed, so much has this been the case, that I sha 
find it convenient, in treating the subject of 
origin of these vessels, to refer to the physi 
logical views of the periods during which th 
successive opinions have been broached. Th 
only other observation I shall make on enterit 
upon this difficult and still obscure subject i 
that the chyle seen on the coats of in 
testine, contained in its proper vessels, so near 
to the villous tunic, has tempted anatomists t 
confine their observations perhaps too muec 
to this one-absorbing surface, with the fixe 
intention of applying the information thu 
gained, to the whole system ; whereas the fluic 
contained in the chyliferous vessels differs 
much from that of the rest of the system, tha 
it is not very improbable that the former which 
admit particles of matter should posSess ori- 
fices, while the latter should receive its con- 
tents by imbibition without peoweeer orifices, 
which, in fact, is the opinion held by two em 
nent physiologists, who have paid considerak 
attention to the subject, Magendie and Cruveil- 
hier. The first opinion with respect to the 
mode of origin of the lymphatic vessels which 
I shall consider is that by open orifices. aq 
Many investigators at various peri nave 
attributed open orifices to the radicles of th 
lymphatic vessels; indeed, this has been the 
prevailing opinion till within the last few 
years. Asellius, the discoverer of that part of — 
the system which is connected with the intes- 
tines, imagined that his “ vasa lactea”’ com 
menced by open mouths from the interior o 
the intestine. His words are, “ ad intesti 
instar hiant spongiosis capitulis.” The first dis 
coverers of the rest of the system, the ** va: 
lymphatica,” did not attribute to them the fum 
tion of absorption, but regarded them as destine 
to assist the veins in returning the cireulat 
fluids to the heart. They supposed them, the 
fore, to be continuous with those arteries whic 
admitted a colourless fluid only, while th 
veins in a similar way received their conten 
from the arteries conveying the red blood. Th 
lymphatics properly so called were not con: 
dered to possess open orifices at their orig: 
until they were generally recognized as shar 
with the lacteals, the important office of abst 
ing fluids, as well as conveying them towar 
the heart. It was not fairly established antil 
the time of the Hunters, that these vessels 
formed part of the absorbent system, alth 
Glisson and Hoffmann had expressed thi 
opinion to this effect, a few years after the dis 
covery of the lymphatic vessels. But to + 
justice to this part of our subject, it will b 
