PLEUROPNEUMONIA. 
837 
ance, due to the intersection of the mass of dark blood, with 
long lines of white fibre ; but the comparison of the aspect 
of the inoculated tail with the consolidated lung is purely 
fanciful. 
Inoculation, if properly performed, is practically a harmless 
operation, requiring but little skill in the operator, but much 
care in the selection of materials and the after treatment of 
the animals to prevent them inflicting injury upon the part 
by rubbing against projecting bodies. Mr. Priestman ope- 
rated, between the years 1859 and 1865, on 4477 cows, and 
of these only 30 died from gangrene as the result of inocula- 
tion. Experience has definitely proved that inoculation is 
not a certain preventive of pleuropneumonia; but the balance 
of evidence is in favour of the conclusion that the disease is 
much less prevalent in inoculated than in uninoculated 
herds, and also that it ceases more quickly when inoculation 
is practised immediately upon the detection of the malady 
in a district than it does when no precautions are taken; but 
it is necessary to add that equally good results have attended 
the adoption of such preventive measures as isolation and 
disinfection. 
The precise value of inoculation, as a means of arresting 
the spread of pleuropneumonia, has never yet been ascer- 
tained, and probably never will be, as the solution of the pro- 
blem would necessitate the carrying out of experiments on a 
grand scale over a large extent of country, involving a much 
greater outlay of time and money than under all the circum- 
stances could be reasonably incurred. 
Isolation . — As a preventive of contagious disease no mea- 
sures can be more effective than perfect isolation ; but to 
properly carry into effect any system of complete separation 
of diseased and healthy animals demands an amount of per- 
sistent watchfulness that cannot easily be insured. The 
system of isolation is based on the principle of preventing 
the contact of healthy animals with those affected with dis- 
ease, and the restrictions should apply equally to all sub- 
stances which have been in contact with the diseased animals. 
In every instance regulations must be made to meet the 
necessities of the particular case ; and, therefore, no precise 
directions can be given. It scarcely need be affirmed that 
the slaughter and burial of infected animals is the most suc- 
cessful method of diminishing the number of centres of infec- 
tion ; but in pleuropneumania there are economic considera- 
tions which stand in the way of the adoption of the stamping- 
out system, and unless the plan were adopted with equal 
energy all over the country at the same time no substantial 
