704 
E. E. BLACK. 
that this one that died had genuine cholera, judging not alone of 
the pathological changes, but in part from the fact that the neigh¬ 
bor across the fence lost all of his young hogs with the disease. 
Another drove of sixty-five was vaccinated where about a dozen 
had died and the ravages of the disease were checked by the loss 
of only three more. 
I could give many more examples like the above but do not 
care to take your time on specific cases, but will say as a whole 
that in no cases where I have vaccinated before the infection was 
present, has it ever made its appearance, and in every case where 
it was present I was enabled to check it reasonably soon after 
vaccination. 
In all of my vaccination I used the single method. On ac¬ 
count of using the single method I find that after vaccinating an 
infected herd, one will become sick occasionally, but will recover. 
This I attribute to the reaction which brings about the lifelong 
immunity caused by the hog taking into his body large doses of 
the infection secured by natural methods. 
One question I would like to hear discussed is how long does 
immunity by the single method last, providing the infection does 
not become present. Some reports say that the protection runs 
out in three weeks, but my experience is that, so far, I have had it 
last for over four months in five different herds and in several 
more for two or three months. 
About fifteen weeks ago I started a test by vaccinating two 
healthy shoats weighing about fifty pounds each and placing in a 
bunch of hogs where all that took sick died, some we sold and the 
remaining old sows died, so it certainly looks as though a very 
virulent form of the disease was present. To-day these two pigs 
are as healthy as can be, and have slept continually in the pen 
where all died. One of them showed the disease, which kept her 
off feed for about three days. 
I am at present conducting another similar test, but it is so 
recent that results cannot be ascertained. 
One more thing I wish to mention is that there is undoubtedly 
a strengthening by vaccination to the whole system in apparently 
