CONTAGIOUS DISEASES OF ANIMALS. 
109 
This method, it will be observed, obviates the main objec¬ 
tions to the ordinary inoculation. By it there is no germ intro¬ 
duced into the animal system, nor any laid up in the buildings 
where the inoculated beasts are kept. The method therefore may 
safely be applied to one of a score or a hundred susceptible cattle 
without endangering the rest, and the building where a thousand 
cattle have been operated on in this way may be at once filled 
with as many more fresh and susceptible animals without disin¬ 
fection, yet without any danger of evil consequences. 
The method is therefore incomparably superior to any other 
that has been hitherto employed, and in special cases may be re¬ 
sorted to with excellent results. The objections to its exclusive 
use are those that apply to all measures that come short of a 
speedy extinction of the disease: 1st. The keeping of diseased 
animals for the production of the virus is not without its dangers. 
2d. The application of the method over a wide district is neces¬ 
sarily slow. 3d. Its application to districts extending over six 
different States would entail a vast amount of machinery, and the 
perfection of the work would suffer in various ways; operators 
would fail for lack of care or ability: cattle would escape notice 
and afterward fall victims to disease, and the incessant additions 
of susceptible animals by birth and otherwise would present a 
serious difficulty. 4th. To operate on animals most satisfactorily 
it must be done before they have entered the infected herd, and 
this would necessitate places of detention for such store animals 
outside the infected districts and a considerable additional delay 
and outlay in the traffic. 5th. The expense for all this machinery 
would be largely prohibitory of the practice. 6th. Finally, we 
cannot expect of this, any more than of any other inoculation, 
that it will prove absolutely protective in every case. We meet 
with second attacks of small-pox, measles and even of lung plague. 
We cannot therefore hope that we can altogether protect such 
exceptional animals as have a great inherent susceptibility to the 
lung plague. These exceptional cases forbid that we should 
adopt this as an exclusive method when we can resort to one 
which is absolutely certain in its results. This method may be 
of the greatest value for the protection of individual herds where 
