18 Experiments on the Development of the Liver-fluke. 
It is possible that the failure of experiments may be due to 
the artificial conditions under which the animals experimented 
upon are necessarily kept. Zeller relates * that he was unable 
at first to rear the adult form of Leucochloridium jmradoxum in 
birds kept in confinement, and had to perform his feeding ex- 
periments upon young birds in the nest, which were then fed by 
their parents. In this case it will be advisable to repeat the 
experiments under improved circumstances. 
4. Investigation of " Sheep-rotting " Fields. — The problem of 
the development of the liver-fluke may be attacked from another 
point, viz. by visiting the scene of actual infection, examining 
the conditions of the ground, and the circumstances which favour 
the contraction of the parasite, studying the fauna and examining 
it for larval forms of Trematodes. With this view a large 
number of farms have been visited in the neighbourhood of 
Oxford, where the outbreak of the disease was very serious in 
1879-80, and some of the more interesting and important 
observations will be briefly noted. In these investigations I 
am especially indebted to valuable assistance from Professor 
Rolleston. 
Wytham. — There was here a well-marked case of upland in- 
fection, and it appeared to be so free from sources of error, that 
numerous visits were paid to it, both by day and by night, and 
the fauna thoroughly investigated at the time which is supposed 
to be most dangerous for the contraction of the fluke-disease. 
Rot first appeared upon this land in the autumn of 1879 ; the 
tenant had held the farm for over forty years, but had never had 
a. single case before. He lost more than forty sheep, and even 
his cattle suffered from the fluke. None of the neighbouring 
farmers had any rot amongst their flocks. The sheep had been 
kept entirely on five fields, situated on the side of a hill, and 
quite above the reach of any floods ; they were not turned on to 
arable land, but some hay and clover was brought to them, and 
their water they got in the fields. The ground on the whole 
appeared fairly good, most of it distinctly sloping, but it lies 
upon the Oxford Clay, and in places there are depressions which 
remain moist, or even a little marshy, in dry weather. The 
summit of the hill is covered with woods containing much game, 
and rabbits were seen about these fields in considerable numbers, 
and are said to have suffered severely from flukes. The disease 
was very likely introduced by them, as their droppings contain- 
ing eggs would be spread all over the fields. A small rivulet 
rises in the woods above, and flows down through these fields ; 
troughs are placed in its course, and it was from these troughs 
* ' Zeitschrift fiir wissenscliaftliclie Zoologie,' 1874. 
