EXPERIMENTS ON PLEURO-PNEUMONIA. 357 
method of infusion into the blood-stream offered was, that 
from fifty to a hundred times the quantity of liquid could 
be introduced at once, and thus the chance of infection be 
vastly increased. 
Fourteen animals were thus inoculated. The instrument 
employed was a syringe, capable of containing two drachms 
of virus, and furnished with a slender, sharp-pointed steel 
tube. The point was made to enter the principal vein by 
which blood returns from the back of the ear, and w r as 
usually secured by a ligature. The syringe was then slowly 
discharged, the greatest care being taken to avoid contact 
with the cellular tissue. It was often unnecessary to divide 
the skin. The whole operation was conducted without any 
appreciable suffering to the animal. 
In the first batch of eight animals the operation was, in all 
but one, performed twice in each case, at an interval of several 
weeks, with a view to greater certainty of result. With the 
exception of a small prominence which marked the seat of 
the inoculation, and subsided in a few days, it was in general 
followed by no morbid effects, either local or constitutional. 
In one instance, however, that of an old cow, unfavorable 
symptoms presented themselves on the sixteenth day after the 
infusion. On that day the bodily temperature, which at the 
time had been natural and had until then continued so, rose 
to 103'Q° Fahr., and on the day following to 105'6°. At this 
point it remained until the twenty-second day, after which it 
declined till death, which occurred two days later. The rise 
of temperature was attended with other signs of fever, and 
with difficult breathing, which continued to the last. The 
post-mortem examination revealed that the cause of death was 
an acute double pleurisy; but in addition to this there were 
appearances which showed that the animal, wffiich was thir¬ 
teen years old, had suffered from chronic lung disease of very 
old standing. This, although not the immediate was the 
predisposing cause of death. The immediate cause was, I have 
no doubt, the infusion, which, acting on the pre-existing 
disease, occasioned consequences to which a healthy animal 
would not have been exposed. It is perhaps desirable to add 
that the affection of the pleura from which this animal suffered, 
although properly called a pleurisy, was of an entirely different 
kind from the pleurisy which forms part of pleuro-pneumonia. 
The sub-pleural tissue, which in the contagious disease is the 
principal seat of alteration, was in this animal entirely unaf¬ 
fected : nor were any of those characteristic changes in the 
lung tissue observed 'which have been so well-described by 
Mr Yeo in this Journal. We are therefore justified in con- 
