INOCULATION OF SHEEP FOR SMALL-POX. 387 
sheep-pox. The virus of this disease is, therefore, subtile and 
fearful, since not only animate but even inanimate objects that 
have come in contact with animals who have sojourned in the con- 
tagious atmosphere may become agents of transmission. 
4. Observation has positively ascertained that the sheep-pox 
pustule contains within its inclosures, from the second or third day 
of its appearance to the eighteenth or even twentieth of its dura- 
tion, a virulent fluid, capable of transmitting the disease. The 
contagion of the disease, therefore, must last for fifteen or sixteen 
days, at least, out of the twenty-five or thirty that it takes to run 
through all its stages. 
5. Although the constitution, age, breed, and condition of the 
animals affected with the pox, as well as the season and salubrity 
or insalubrity of the folds, exercise considerable influence over the 
character, malignant or benignant, of the pox, observation appears 
to have demonstrated that contagious virus derived from a ma- 
lignant natural pox produces a benignant pox, and vice versa. 
Whatever, however, may be the malignity or benignity of the 
disease with which their sheep are threatened, farmers have reason 
ever to be alarmed at its appearance among their flocks. 
6. Observation has taught us, that idiopathic small-pox, or that 
which is communicated naturally through some volatile virus, does 
not attack at once the whole flock, but shews itself by three and 
sometimes four successive attacks known by the name of bouffees 
or lunees, and that the duration of each of them is from twenty-five 
to thirty days ; hence the total duration of the natural sheep-pox 
in a flock is at least from three or four months. So that, supposing 
during the time that the disease should be transmitted through 
contagion, it follows of necessity that the sanitary measures pre- 
scribed by the acts and regulations of parliament, such as seques- 
tration in the pens or distribution in the folds, ought to be main- 
tained for at least three months. 
7. The mortality occasioned by the pox in flocks is very variable. 
In localities wherein the disease is in a measure annual, and where 
the breed is indigenous and local, the losses are inconsiderable, 
and great mortalities exceptional ; while in all places wherein are 
bred, reared, and sometimes fatted, sheep of an exotic breed, pure 
or crossed, sheep-pox, cceteris paribus, is productive of great 
losses. 
Excessive heat, as well as excessive cold, salubrity or insalubrity 
of situation, fat or lean condition, tender age, pregnant state of the 
females, are all so many circumstances tending to augment the 
mortality ; while the opposite conditions diminish it. 
With a view of arriving at a mean estimate of mortality in the 
case of sporadic sheep-pox, enzootic and epizootic, I have made 
