80 
The Rot in Sheep. 
shows itself more particularly during- the summer months, though 
in its progress the disease is carried over to the autumn, through 
the winter, and even into the next year. 
His words are, that "floods in the latter part of the summer 
are generally precursors of considerable destruction from rot. 
The meadows when the water clears away must be in the highest 
degree dangerous. The grass at this time had begun to die, the 
outer leaves and some of the stalks were perishing ; they wanted 
only the agency of heat and moisture to run into perfect decom- 
position. The rain comes, and with it the summer's heat, and 
the decomposition is rapid, and the extrication of poisonous 
gases profuse." 
Again, " The nature of the herbage and the character of the 
plants which the soil produces have nothing to do with the 
development of the rot. It is caused simply by the extrication 
of certain gases or miasmata during the decomposition of vege- 
table matter, under the united influence of moisture and air." 
It is, however, not a little singular that Mr. Youatt, in stating 
facts with reference to the disease, should name one which 
positively contradicts his theory with regard to miasm ; and 
he appears to have done so Avithout noticing it at the time. 
The fact to which we allude is thus given : — " A farmer, in 
addition to other land, had a dry, hilly sheep-pasture, which he 
stocked, rather hard. In a hollow place of that pasture was a 
swampy pond, which was preserved for the sake of supplying 
the wheel of the thrashing-machine. The farmer, notwith- 
standing the dry and favourable nature of his sheep-pasture, had 
occasional losses from rot in his flock. He fenced in the pond, 
and prevented the sheep from having access to the swampy 
border that surrounded it, and the rot entirely ceased." 
The circumstance of the cessatioti of the disease at once nega- 
tives the idea propounded with regard to miasm. If the pond 
had been thoroughly drained, the water being thereby entirely 
removed, and the character of the soil improved, we can under- 
stand that miasmatic vapours would have ceased to arise from it ; 
but the pond still remaining as a pond, with its swampy border, 
miasmatic matter would spring therefrom just as much when it 
was enclosed with an ordinary fence as when it was open. 
The theory of miasmata being the cause of rot has already been 
shown to have originated with Dr. Harrison in 1804, although 
long antecedent to his time the injurious effects of " bad air " had 
been vaguely alluded to. We may further remark that the mias- 
matic theory was revived by Davy in his essay on ' Bane,' pub- 
lished just ijefore the writings of Youatt." 
D. Price, previously quoted from, rightly observes that " many 
objections might be urged against this theory, however plausible 
