254 
Liver Rot of Sheep 
Table I. Table showing Rainfall and Rainy Days. 1910-1912. 
Aberystwyth Gogerddan Machynlleth 
1910 
1911 1912 
1910 1911 1912 1910 
1911 
1912 
Rain 
42-18 
37-54 41-70 
54-51 46-45 -56-75 66-54 
55-65 
70-71 
Days 
221 
180 228 
233 190 227 238 
194 
229 
Table II. 
Table showing Rainfall and Rainy Days. 
Aberystwyth, 1905-1915. 
Year 
1905 1906 
1907 1908 
1909 1910 1911 1912 1913 
1914 
1915 
Rainfall 
31-37 36-88 
35-46 33-56 
33-65 42-18 37-54 41-70 41-97 
36-12 
34-65 
Days 
196 211 
211 172 
188 221 180 228 210 
202 
196 
Table II illustrates the relation between amount of rainfall and 
number of raining days for Aberystwyth for the period 1905-15. It has 
already been shown how important a part drought plays in the bionomics 
of L. truncatula hence let us examine the records for evidence of marked 
droughts. Figs. 3-5 illustrate the monthly rainfall for Aberystwyth for 
the year 1908 (a dry year) and 1912 (a wet year) also 1915 a season 
that had a marked effect upon L. truncatula since almost all in the Area 
were killed. 
In the charts (p. 255) the rainy days in each month are shown, and 
further the relation between days and inches per month. It must be 
borne in mind that relative evaporation plays an important part, and 
that a rainfall that would suffice in winter would not necessarily do so in 
summer, again, a monthly rainfall say in February or November of 
three inches distributed over 20 days would in all probability keep 
L. truncatula alive, whilst in August falling in thunderstorm showers of 
brief duration it would probably amount to a physiological drought 
sufficient to kill a considerable percentage. 
Much, as I have said, depends upon the situation, but the factors 
involved are complex and each spot would need to be considered 
separately to gain a complete understanding. Still, a good deal can 
be learned from the charts given. 
I have also made a close examination of the Aberystwyth rainfall 
data from 1901 to 1915 noting the number and length of dry spells of 
more than five days. The longest rainless spell was one of 23 days in 
September but, on the average, dry spells of more than 10 days are rare, 
and the dryest periods are usually those of light rainfall spread over a 
considerable period in summer. In July, 1911, for instance, only -83 
inches fell during that period, followed in August by 5-56 inches on 15 
