550 
PROFESSOR WALLEY. 
mischief, too, in the case of other districts, and especially in 
Fife, for, with one or two exceptions, such centers have been 
discovered in every lot of animals that has been brought to 
our abattoirs for slaughter as healthy animals that had been in 
contact with diseased animals. 
Wrong Conclusions. 
Moreover, these infective centers are often the means of 
giving rise to wrong conclusions as to the particular animal 
which has introduced the malady ; and one example of this I 
will give you. A few months ago an outbreak of pleuro¬ 
pneumonia took place in an Edinburgh byre. The first case 
that was brought under my notice was in an Ayrshire cow 
that had been purchased about six or eight weeks previously 
at Dalkeith ; but on inquiry it was discovered that the bulk of 
the cows in the stock had been brought from a byre in the dis¬ 
trict of a neighboring local authority a short time before the date 
of the outbreak, and in slaughtering out the stock, one ani¬ 
mal that had been purchased seven months previously from 
one of the lots of contaminated Cumberland cows sold in the 
Edinburgh market was found to have a very old encysted 
pleuro-pneumonia lung, or portion of a lung, in a state of 
active degeneration, and two others were subsequently dis¬ 
covered with cysts of a more recent date. In the preinocula- 
tion period in this city we found that in all the instances in 
which the disease fingered in a byre in spite of our efforts to 
suppress it, its continuance was coincident with the uncon¬ 
scious retention in the byres of cows in whose lungs old 
cysts existed, and that so soon as these were discovered and 
got rid of, the disease disappeared also. 
In the inoculative period my experience was an identical 
one, and if time permitted I could give you particulars of 
case after case in which, in spite of inoculation, the disease 
continued to develop until the animals with old centers in 
their lungs were discovered and slaughtered. 
Inoculation Impotent. 
The argument that inoculation renders these old pulmo¬ 
nary centers harmless is one that will not bear the slightest 
