ON THE MESENTERIC VEINS. 
35 
These physiologists found that quicksilver injected into the 
absorbents of the intestinal canal easily reached the mesenteric 
veins and the vena portee, and this communication was found to 
take place in the mesenteric glands. By means of this commu¬ 
nication, they explain the appearance of streaks of a substance 
like chyle, which is perceived in the blood of the vena portae after 
taking food ; a fact which has been frequently observed by other 
anatomists.’’ 
In reply to the suppositions which have been advanced by 
these physiologists, and which are, “ that either all the lacteal 
vessels do not enter the thoracic duct, and that a part of them 
join the veins wdiich form the vena portae, and further, that the 
communication of the lacteal vessels with the mesenteric veins 
and vena portae has been found to take place through the glands 
of the mesentery by the injection of quicksilver into the lacteals 
of the intestinal canal,” I have only to add, that from my own 
examinations and injections, as also those of the first-rate anato¬ 
mists in this country, no communication whatever of this kind 
has yet been found to occur. 
And as regards the appearance of streaks of a substance 
like chyle being found in the blood of the vena portse after taking 
food,” I have only to observe, that a similar appearance of the 
blood taken from the arm of the human subject has also very 
frequently been observed ; of the real nature and cause of both of 
which I shall endeavour to give a full explanation when I come 
to treat of the blood, lyiirph, and chyle, and the varied changes 
and appearances which these present during their course through 
the whole circulatory system. 
Dr. Copland further observes, that from these and some other 
experiments, “ it was found, that on examining the blood taken 
from a branch of the mesenteric vein of a dog, to which sulphuro- 
prussiate of potass had been given, no streaks of chyle were 
present, but the saline matter was perceived. From this and 
other experiments, they conclude that the veins of the intestines 
appear particularly to absorb heterogeneous substances, such as 
those already particularized (alcohol, gamboge, indigo, &c.), 
whilst the lacteals take up nutritious matter ; and, consequently, 
that substances taken into the digestive canal may pass into the 
mass of blood, first, through the lacteal absorbents and thoracic 
duct; secondly, through absorbents which are united with veins 
in the mesenteric glands; thirdly, through the radicles, or the 
commencement of the mesenteric veins, which ultimately form 
the venaportee.” 
The first and third of these positions have already been fully 
treated on; and I should consider that the various facts which 
