Report on Liver-Rot. 
151 
district, and on one t'iirm alone seven cows died in one week 
I'rom diseased liver. 1 did not in these cases examine the 
calves. 
Evidently in these cases of flukes occurring in Iambs and 
calves at birth, or immediately after, the cercarian forms of the 
duke have been picked up by the dam, probably during the 
latter half of gestation. Carried in the blood, instead of being 
deposited, as is usually the case, in the maternal liver, they must 
have passed, as the mother's blood freely does, into the foetal 
circulation, and been arrested in the liver by that unexplained 
affinity which certain organs exert over both normal and abnormal 
blood constituents. Little more than a month's location in the 
ffetal as in the adult liver would bring the immature flukes to 
the full perfection in which they have been found by Mr. Evans 
and a few other observers. These cases of congenital parasitism 
must, however, be extremely rare. Hundreds of lambs dropped 
from ewes in the last stages of rot have been examined without 
finding any traces of flukes, of ova, or of other embryonic forms. 
Thousands of lambs and many calves from fluke-infested ewes 
and cows, thrive and grow without any manifestation of fluke 
infestment. , Calves or lambs do not swallow, as has been 
popularly supposed, fully-developed flukes, and, judging from 
experiments made by Professor Simonds, Gerlach, and others, 
adult flukes, even if swallowed, produce no effects. 
The ultimate host, be it ruminant or rodent, young or old, 
appears to swallow the immature cercaria^ in their encysted form. 
Within five or six weeks, some authorities say within a month, 
these cercaria? may pass to the liver, and become fully-developed 
flukes. In the authenticated cases mentioned by Mr. Rawlence 
and other observers, occurring in house-fed calves of eight or 
ten weeks old, there was thus ample time for infestment in the 
usual manner after birth. Neither calf nor lamb can get the 
parasite in the milk as yielded direct from its dam. There is 
no evidence of cercariaj passing from the blood into the milk- 
gland and thence being secreted in the milk. The calves and 
other juveniles doubtless swallow, as their dams might do, the 
cercariae whilst nibbling a morsel of cut grass, clover, or cabbage, 
on which the parasite lorm is lodged. The water used to wash 
or swill milk-buckets may contain and leave in the buckets 
some of the penultimate forms which may be taken by the calf 
in its next meal of milk. Perhaps more probable still, the cow 
or ewe lying on the pasture, or straying through it, or drinking 
from a stagnant pool, gets attached to her skin or wool these 
cercaria?, which thence would be readily licked up by the calves 
or lambs, and in a few weeks matured flukes would be found in 
the liver. 
