Liver Rot of Sheep 
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adults, measure about 5 mm. in length. They in turn deposit ova during 
June-July. Drought usually limits further progress until the late 
Autumn, the snail being often very scarce during August-September. 
6. Desiccation speedily kills L. truncatula. Local environmental 
conditions—rainfall, aspect, soil, vegetation, etc.—play a very important 
part in respect to its survival. Rainfall and its distribution through the 
year is the most important factor governing the increase, spread, and 
infectivity of the snail. 
7. The ova masses dry rapidly and then resemble a hard incon¬ 
spicuous scale. They resume their former size and shape when moisture 
returns, and many appear to be able to hatch subsequently, though 
the amount of desiccation they will withstand is not yet determined. 
In spite of prolonged droughts, L. truncatula re-appears, unless ditches, 
etc., have been cleaned out. 
8. Roadside ditches are very frequently inhabited by infected 
snails and the drainage from them may be the cause of cases of rot. 
9. Cercariae of D. hepaticum were obtained from L. truncatula in 
large numbers practically throughout the year; but not from snails 
measuring less than 4-5 mm. in length. Seventy cercariae were given 
off naturally, within 48 hours, from one specimen measuring 7 mm. in 
length. Heavily parasitized snails are adversely affected. A few 
cercariae, resembling those of D. hepaticum were obtained once from 
L. peregra. 
