VOL. XIV.] PHILOSOPHICAL TRANSACTIONS. 103 



I ordered about 3 pints of broth to be given to a dog, which had been kept 

 fasting 24 hours ; and opening him 4 hours after this, I observed that the 

 lacteals, beginning at the duodenum, were very much distended with the 

 matter of the last meat : all the lacteals, that I saw at first, were of a perfect 

 white colour; several of which I pressed between my fingers, drawing them 

 from the circumference toward the centre of the mesentery, by which means I 

 found, that the chyle, contained in these vessels, appeared white, when it ran 

 in a shallow stream, as well as when it filled the lacteals: viewing the rest of 

 these vessels along toward the cascum, I observed that, near the middle of the 

 intcstinum ileum, they began to be of a more diluted white; and a little farther, 

 they were really pellucid, and as turgid, to appearance, as those that were 

 white; after which, turning back again toward the stomach, I saw the same 

 vessels in as great numbers as at first, but the colour of most of them changed, 

 being now all pellucid. The same thing happened in a dog kept fasting 2 days, 

 and then opened 3 hours after he had lapped 3 pints of milk, part of which 

 was seen in the stomach of the dog: about 15 of the lacteals, arising from the 

 duodenum, were white; above 100, proceeding from the intestinum jejunum 

 and ileum, were more or less transparent; as also were those of the duodenum 

 at the latter end of the operation. 



1 . The 1 st experiments sufiiciently prove, that the lacteals convey not only 

 chyle, but also another humour, separated from the blood, and now returning 

 to it again ; which may be seen purely by itself, without any mixture of chyle. 



Now as far as I can judge at present, it seems not unreasonable to derive at 

 least part of this liquor from the hollow of the intestines ; if we consider that 

 the pancreas, and glandularum plexus fragiformes^ not to mention the liver, 

 daily discharge a liquor into them. It seems probable, from the same experi- 

 ments, that the lacteals are very seldom, or never, all empty al the same time; 

 for though the chyle flows only in certain tides, or periods, pro ratione inges- 

 torum ; yet the refluent liquor, running in a more constant stream, does, when 

 there is no chyle going in, keep the lacteals from being absolutely empty. And 

 it is farther evident, from the same experiments, that this refluent liquor is, in 

 its own nature, transparent ; and passes such through the lacteals, after long 

 fasting, when no chyle is mixed with it. 



The experiments, both. of the 2d and 3d kinds, seem to intimate, that a 

 great part of the chyle itself is, in its passage through the lacteals, altogether 

 limpid. Against which if it be objected, that some of the lacteals were in a like 

 manner pellucid, in all the experiments of all the 3 kinds, and therefore it does 

 not appear but that they may be filled with a refluent liquor in the last two 

 cases, as well as they were in the first case. To this objection it may be re- 



