106 
J. LAW. 
1st— Keeping Insusceptible Breeds. —Some breeds appear to 
be somewhat less susceptible to lung plague than others. In 
some this has been acquired by a long exposure of their ancestors 
to the plague, so that the more susceptible strains of blood have 
died out, leaving only those that have a greater power of resis¬ 
tance to this contagion. This is merely “ the survival of the 
fittest.” In other cases cattle that are defective in muscular 
development, in loose connective tissue and in the lymphatic 
apparatus show a somewhat diminished susceptibility as com¬ 
pared with those of an opposite habit of body. But in neither 
of these cases is the susceptibility ever completely eradicated 
from the race or family. Each of these conditions will to a very 
slight extent reduce the losses, but neither separately nor together 
can they arrest the propagation of the poison, nor prevent the 
progress of the disease. They are, therefore, only to be sought 
on the unfenced pasture ranges, covered with cattle, where the 
permanence of the disease is already assured, and where no hope 
of its extinction can be held out. In other circumstances we 
can do incomparably better. 
2d— Passing the young through the "disease .—In badly in¬ 
fected districts shrewd dairymen have profitably resorted to the 
exposure of calves to the infection, realizing that the pecuniary 
loss through the death of the individual animal at this age was 
small, while the survivors could afterwards be exposed to infec¬ 
tion with impunity. 
3d— Inoculation with the fresh virus from the diseased lung .— 
A more economical methed is the inoculation of the susceptible 
cattle in the tail, so as to exhaust the susceptibility. This, when 
properly managed, does not cause a loss of more than one or two 
per cent., and the survivors acquire as perfect an immunity as 
vaccinated people have from small-pox. This inoculation is ex¬ 
tensively practiced in Belgium and France, is obligatory in 
Holland, and is almost universal in Australia, New Zealand, 
Tasmania, South Africa and in certain parts of Great Britain 
and America. It has greatly diminished the losses in these 
countries, but in no one of them has it put an end to the plague. 
In the city of Edinburgh, where it is supplemented by the 
