*262 
Liver Rot of Sheep 
A considerable number of these spots had to be used in order to check 
results and gain mass of data. 
4. These ditches are without doubt the cause of many of the 
sporadic cases of rot that are constantly turning up on otherwise free 
farms. 
5. They are also responsible for more serious infection to sheep 
that stray from mountains and fields to graze by the road sides. Bad 
fences, gates, and walls (or their entire absence) contribute largely 
to this state of affairs. I know of several flocks that have been cprite 
seriously affected through being allowed to graze by infected roadside 
ditches, while other neighbouring flocks not allowed to do so, escaped 
loss. 
6. Infected water from these ditches is frequently allowed to flow 
over grass fields in a most dangerous manner. Almost every roadside 
ditch within the Area contains running water, and where conditions 
are suitable L. truncatula is to be found and very frequently heavily 
infected, and this infection is liable to be kept up from droppings of 
sheep either moved along the road or kept in adjacent fields. The 
water supplying these ditches is derived from: 
(a) Direct rainfall. 
( b ) Springs arising in fields adjoining the road. 
(c) Field drains. 
(d) Seepage from ground on a higher level than the road. 
(e) Ponds. 
(/) Frequently a combination of these causes. 
Where the slope is a long one (as is frequently the case in the 
Aberystwyth Area) the water is often led into a field in order to avoid 
flooding the road during heavy rainfall, and this may occur several 
times on a long hill or gradient. The water in each of these sections 
of ditch may have a separate origin and must be considered separately, 
and may or may not contain L. truncatula , which may or may not be 
infected. 
Again, should even heavily infected water flowing into a field be 
conducted thence by a ditch which is kept open and reasonably free 
from vegetation, rot may be very rare or absent in sheep grazed there, 
because cercariae cannot become encysted upon the grass. The next 
field below, possibly belonging to another holding, may however become 
infected. The key seems to lie in a regular and systematic clearing 
out of ditches by those responsible, whether road authority, owner or 
tenant. Much land would be improved and loss in many cases avoided. 
