558 Louping-ill in Sheep. 
the year, and in numbers that would make any attempt to destroy 
them utterly futile. 
If future investigations should confirm the suspicion that ticks 
are instrumental in infecting the lambs, it is possible that something 
in the way of prevention might be done, by dipping or smearing of 
the young lambs with some substance that would prevent the tick s 
from attaching themselves. On the other hand, if infection takes 
place by way of the alimentary canal or the navel, it is difficult to 
imagine a feasible method of prevention. 
2. Indigestible substances in the stomach or intestines . — The 
post-mortem examinations which I made in Northumberland appear 
to indicate that in a considerable proportion of the cases diagnosed 
as louping-ill in lambs the illness is caused by the ingestion of 
such matters as dried grass, wool, and sand. In the cases in which 
the presence of grass and wool in the fourth stomach was noted, 
these substances were compacted together into a ball-like mass, 
which in some instances was as large as a hen’s egg. It appears 
probable that the lambs, having reached the age at which they 
naturally begin to eat grass, ingest the dried stems simply from 
lack of a more succulent herbage, and it is plausible to suppose 
that this in large measure is the explanation of the statement that 
louping-ill attacks the most thriving lambs (which would be the 
first to take to eating grass) and is most prevalent in cold backward 
springs (which retard the growth of the young grass). It is no easy 
matter to suggest a feasible method of averting the danger, since in 
practice it would hardly be possible either to eat the pasture so bare 
as to leave none of the withered grasses over the winter, or to remove 
the young lambs to succulent pasture before they begin to take to 
solid food. 
If, as seems not improbable, the wool which is found mixed with 
the dried grass in the fourth stomach is pulled from the neighbour- 
hood of the udder during the lamb’s efforts to seize the teat, some- 
thing in the way of preventing this might be done by clipping the 
long wool from the mammary gland and its neighbourhood at 
lambing time. This operation — the so-called “ udder-locking ” — 
was, I believe, at one time more frequently practised than it is at 
the present day. 
Previous Investigations. 
By way of conclusion I may briefly indicate the results obtained 
by others who have recently investigated this disease. 
In the year 1879, the Teviotdale Farmers’ Club appointed a 
committee to investigate the cause of louping-ill, and in the follow- 
ing year the committee published its report. The report is interest- 
ing chiefly on account of the extraordinarily discrepant views 
quoted in it regarding the symptoms and cause of the disease, 
and the conditions under which it manifests itself. No one can 
read the report without feeling that much of the difference of 
