54 
THE VETERINARIAN, JANUARY 1, 1870. 
Ne quid falsi dicere audeat, ne quid veri non audeat. — Cicero. 
INOCULATION AS A PREVENTIVE OF CONTAGIOUS 
PLEURO-PNEUMONIA OF CATTLE. 
Once more the question of the efficacy of pleuro-pneumo- 
nia inoculation is to be discussed, and experiments are to 
be tried, for the purpose of determining — not the possibi- 
lity of communicating the affection by the introduction of 
the exudation from a diseased lung ; but whether or not cattle 
which have been inoculated with it are thereby protected 
from an attack of the natural disease. All this sounds very 
well at first ; but a little consideration will suffice to show 
that the proposed investigation is not quite such an affair of 
plain sailing as it seems. 
Unfortunately, scientific men and also non-scientific men, 
or as the favourite term is practical men, are, in reference 
to this question, in a condition of hopeless antagonism, 
not of an active or unpleasant kind, but to the extent of 
having no ideas, modes of thought, or method of reasoning 
in common. It is of no consequence whatever which of 
the two shall carry out the inquiry, they are certain to be 
mutually unintelligible at the last. 
With a very faint hope of averting some of the confusion 
which we foresee, we intend to state the present position of 
the argument as concisely as possible, dealing only with 
facts which have come under our own observation, and 
which bear with some degree of force upon the question 
which is again before the agricultural public. 
To make the matter as clear as may be we shall place all 
speculative points first, and then leaving these proceed to the 
consideration of others which are capable of demonstration. 
Speculation the first relates to the origin of the disease 
in this kingdom. Did it arise spontaneously, or was it in- 
roduced from the Continent in 1840 ? The answer to this 
question is based on a legend of the importation of 
