632 
REPORT AS TO VACCINATION OF SHEEP. 
supply was thus procured, which, however, on trial was like¬ 
wise found to be not more active than ordinary vaccine lymph. 
This point we shall have occasion hereafter to refer to again. 
Finding such unsatisfactory results from these experiments, 
we determined to ovinaie the cow, with a view of procuring, if 
possible, a lymph which would produce more decided action 
on the sheep on being returned to this animal, in a similar 
manner that the virus of human smallpox, after being passed 
through the cow, has been returned to man. For this pur¬ 
pose six cows were ovinated with lymph taken from a natural 
case of sheep-pox, eight punctures being made in th eperineum 
or on the labiapudendi of each cow. No special results fol¬ 
lowed, but some of the same lymph, used at the same time 
on sheep, took readily. The experiments were repeated on 
these cows shortly afterwards with a like result. Within a 
few weeks of this time five other cows, a heifer, and a steer, 
were ovinated after the same manner from a natural case of 
sheep-pox, sets of scratches being used as well as punctures 
on the teats and other parts; but still no sufficient effect was 
produced to enable us to obtain lymph. These experiments, 
so far as they go, show the correctness of that which has been 
stated by several of the continental writers respecting the in¬ 
susceptibility of the cow to take the sheep-pox, and they also 
confirm the experiments which were instituted by ourselves 
in 1848 to determine this same question. 
Although scarcely anticipating any greater success, we 
nevertheless resolved to give trial to the vaccination of pigs, 
and also to the inoculation of them with the virus of human 
smallpox; these animals being omnivorous, and therefore, 
like man, living on a mixed animal and vegetable diet. Pigs 
varying in age from a few weeks to a year old were chosen 
for the purpose. The vaccinations, although several times 
repeated, produced no effect; and the inoculations but very 
slight; no vesication following from either. 
We were thus thrown back upon current vaccine lymph 
for the completion of the experiments, and after a short 
interval the sheep not affected by any of the previous vacci¬ 
nations were vaccinated again, but without any material 
alteration in the results being obtained. Fifty-six sheep 
were next selected for a repetition of the experiments, care 
being taken that some of them should be animals on which a 
former vaccination had had effect. Only 12 of the 56 sheep 
showed any result from the operation; and it is worthy of 
note that no less than 8 of these, or two-thirds, had been 
affected before. Another 50 were selected and vaccinated, 
and 29 of them took the disease; 17 of which, or nearly 
