36 
VIRUS OF SHEEP POX. 
reach to be for a certainty preservative against the natural pox 1 
And why, when both diseases are present in the same individual, 
instead of developing themselves simultaneously, the natural pox 
will become suspended for twelve or fifteen days, and sometimes 
longer, to allow for the accomplishment of the principal phenomena 
resulting from inoculation. 
In collecting virus for inoculation, Lebel, for choice, prefers a 
pustule of a spheroid form, moderate size — such as a good-sized 
hazel nut cut in halves would present — rising well above the sur- 
face, exhibiting either a blush of red or a uniform rosiness, and 
having neither furrow nor eminence upon it. The twelfth day is 
ordinarily to be preferred, though matter may be collected up to 
the sixteenth; nay, a pustule eighteen days old will furnish conta- 
gious virus : and a single pustule of the required form and dimen- 
sions will furnish virus sufficient for three or four hundred sheep. 
A question importantly bearing upon what has gone before is, 
Has the blood of a sheep having the pock the power of commu- 
nicating the disease 1 and, if so, if more so in the natural and con- 
fluent pock 1 and up to what period is this property, supposing it 
to exist, preserved 1 By way of answer to these questions, Lebel 
mentions the following experiment : — 
On the 15th of November, 1834, two lambs, which, up to that 
time, had been kept separate, were inoculated from blood drawn 
from the plat-vein of a sheep in the thirteenth day of his pock. 
The inoculation produced no effect; notwithstanding both the 
lambs took the disease afterwards from inoculation with virus, and 
had pustules rise close by the punctures made by the blood-inocu- 
lations. 
%* This experiment appears to us any thing but satisfactory or 
conclusive. The blood may have been — most probably was — 
infected ; and yet a drop or two of it, or as much as would be 
conveyed upon the point of a lancet, be totally insufficient to 
transmit the disease. To cite Coleman, who was always particu- 
larly happy on this point, a quantity of arsenic might be put into 
a pailful of water, and vet a spoonful of the fluid not poison an 
animal. Transfusion should have been made of the blood of the 
infected sheep, and then the experiment would have had validity. 
And, supposing the sheep had shewn signs of having become 
thereby infected, further inoculation should have been made from 
the pustules upon him. — E d. Vet. 
