Experiments on the Development of the Liver-fluke. 25 
containing a young fluke about one to three lines long, could be 
pressed. When a cut was made into the liver, the surface had a 
mottled appearance, due to a solid yellow substance, and to 
small spots where the substance was inflamed or destroyed, and 
reduced to a red ooze. The bile-ducts could hardly be said to 
be enlarged, and no flukes of any kind could be found in the 
larger ducts. By far the largest number were in the smaller 
branches of the bile-ducts, or in centres of destroyed hepatic 
tissue. They occurred especially near any surface of the liver. 
The young fluke on entering the liver by the bile-duct appears 
to push its way onwards into the smaller ducts, where some 
remain, whilst others penetrate the walls of the ducts and crawl 
forwards to the surface, causing the destruction of the paren- 
chyma as they proceed. Arrived at the suface of the liver, they 
may pass along beneath the peritoneum, as may be seen from 
the long inflamed tracks which they leave behind them, or they 
pierce the peritoneum and set up perihepatitis, and the conse- 
quent adhesion gives rise to the ragged patches of connective 
tissue visible on the surface of the liver when this is removed 
from the body. The flukes may also be found in the peritoneal 
cavity of the animal, as I have seen them in a rabbit. In 
another case, where all the flukes present were of full size, and 
atrophy of the hepatic parenchyma had made some progress, 
several flukes were found at the thin free edge of the liver, with 
the anterior part of the body projecting into the peritoneal 
cavity. The power of the fluke to wander within its host seems 
to be greater than is generally supposed. Mr. A. H. Cocks 
informs me that on examining a Welsh ewe which had died 
from the rot, he found several flukes in folds of the mesentery, 
and others in the uterus. 
The smallest flukes I have been able to discover were found 
in this liver : the two least measured I'l and 1"25 mm. long, and 
a good many others were little more than 2 mm. long. The 
appearance of such small forms may form some guide in search- 
ing for the cercaria. The digestive tract was already very much 
branched, though to a less extent than in the adult ; the spines 
covering the body were present, but extremely fine. In the one 
measuring 1-1 mm, in length the anterior part of body measured 
0'4 mm. only, the posterior part 0'7 mm. 
Leuckart {I.e. p 573) conjectures that the liver-fluke occupies 
only three weeks in arriving at maturity. But the lamb just 
mentioned had been removed from the source of infection 6^ 
<lays before it was killed, and in the interval had been kept on 
dry ground, where rot could not be contracted, and yet some of 
the flukes measured little more than 1 mm., and the largest was 
only 8 '5 mm. long. A lamb of the same flock was killed nine- 
