216 EXPERIMENTS MADE ON SHEEP WITH THE INSECT, &C. 
it was introduced upwards towards the head. To ascertain now 
the quantity of blood which would pass from one animal to 
another in a given time, I allowed it to pass through the tube 
last-mentioned during half a minute, and found by weighing it 
that it amounted to nine drachms. I then placed between the 
two sheep a flexible tube about three feet long (which was formed 
of the two carotids of a horse), and fastened the two ends of the 
pipes which had been already fitted into the veins. The blood 
flowed now evidently from the diseased sheep into the sound 
during a little more than two minutes of time, so that the sound 
sheep received four ounces and a half of blood from the diseased 
one. The bloodvessels were now tied up ; no particular change 
appeared either during or after the operation. After continued 
observation and daily examination of the sound sheep, not the 
slightest trace of disease of the hide shewed itself up to the 14th 
of March, 1828, i. e., during thirty-three days. 
Experiment No. 15. 
On the same day an experiment was undertaken of trans- 
fusing arterial blood from the carotid of another scabby sheep 
into the carotid of the wether sheep used in the third and fourth 
experiments. By observing the same caution and following the 
same method as in the former experiment, the flexible tube was 
fastened in one sheep towards the head, and in the diseased 
sheep towards the heart. Ten drachms of blood were found to flow 
through the tube in half a minute from the last-mentioned sheep ; 
therefore the sound sheep received by the transfusion continued 
through two minutes about five ounces of blood. In this ex- 
periment also nothing particular happened. After observing the 
healthy sheep up to the 15th of March, not the slightest change 
could be discovered in any part of its hide. 
Experiment No. 16. 
An experiment was repeated on a third sheep which had 
already been used in Experiment No. 12, which had remained 
up to this time perfectly healthy. In this instance, however, 
three ounces of arterial blood taken from a scabby sheep were on 
the 15th February, 1828, injected into the arteries by means of 
a squirt. In this case also not the least mark of disease was to 
be found up to the 15th of March. 
From the foregoing experiments the following conclusions 
may be drawn : — 1st, That the scab can be with certainty com- 
municated from one sheep to another only by means of an insect 
(sarcoptes). — 2dly, That the inoculation with the discharges 
