74 
T]ie Rot in Sheep. 
that management, would never affect a slieep in the least; the 
water may flow with impunity all winter, and even to the end 
ot April, but after that the above effect is sure to take place. 
Springs he asserts to be no cause of rotting, nor yet the giass 
wliich rises in consequence, unless they flow. Nor is it ever 
owing to the ground being very wet from heavy rains, unless 
the water flows. This theory of the rot " (adds Young), " upon 
the wliojc, appears satisfactory ; and that part of it which is the 
certain result of experience, cannot be doubted." 
The next author in the order of date (1804) whose opinions 
we shall notice with reference to the cause of rot is Dr. Harrison. 
We have already had occasion to quote from his Avritings respect- 
ing an outbreak of this disease in 1792. 
Under the head of Causes of rot, he says, " the disorder lias 
been imputed — 
" 1st. To a vitiated dew. 
" 2ndly. To a gruft, which adheres to the grass after wet 
weather, in the overflowing of running water. 
" Srdly. To the luxuriant and quick growth of plants in hot, 
moist seasons. 
" 4thly. To grazing upon certain herbs ; of which the Butter- 
wort (^Pinguicula vulgaris), White-rot illydrocotylc vul- 
garis). Round-leaved Sundew {Droscra rotundifolia), and 
the Long-leaved Sundew {Drosera longifolia) have been 
chiefly suspected. 
" 5thly. To Fasiola; hepaticae — flukes, or their ova — being 
introduced into the stomachs of animals by feeding on 
swampy and low grounds in moist weather. 
" Gthly. It is ascribed by Daubenton to poor diet and drinking 
too much water. 
" 7thly. It seems to be occasioned by poisonous effluvia, which 
under certain circumstances are emitted from marshy 
soils." 
Dr. Harrison advances arguments against all these suppositions 
with a view to refute them with the exception of the last, which 
he endeavours to pi'ove is the true and oiihj cause. Speaking of 
the influence of the sun's rays on swampy ground, he remarks, 
" evaporation is copiously performed, and probably some of the 
Avater is decomposed, so as to generate in combination with other 
substances the poisonous effluvia, called miasmata pallidum, which 
occasion the rot in animals." In another place he remarks, " for 
my own part I have declared for several years in various com- 
panies that marsh miasmata are the cause of both agues and 
rot." 
Hereafter we shall offer some remarks on this opinion of 
Harrison's, especially as we find it adopted by modern authorities 
