
SSR Sfar 
this is very striking when compared with the 
sensibility of those born before an epidemic 
of foot and mouth disease. Considering the 
short time immunity lasts it is not to be ex: 
pected that vaccination should confer resis- 
tance for more than a few months. This is 
however not so very important as an epide- 
mic on a farm may last for only a month 
or even less and seldom lasts longer. Immunity 
for about a month orsix weeks is quite suf- 
ficient as the epidemic may be crushed in 
that time. Loeffler also mentions this fact 
(Deut. Med. Woch. 30. Nov. 1905.) 
One of us had been experimenting so 
as tofinda practical way of inducing immu- 
nity since 1912 and succeded in finding a 
process which we applied about two years 
ago with quite satisfactory results. Before 
discribing the method itself, we would give 
a synopsis of the several phases in the shaping 
of it. 
The very first obstacle we met with 
was the difficulty of transporting the virus, 
which was gathered about a mile and a half 
from our laboratory at the Experiment Sta- 
tion of Bello Horizonte. We inoculated the 
gums of several calves but only one of them 
had aphthae. 
When the distance was longer we used- 
pure glycerine, or 30 0/0 and 50 0/0 glyceri- 
ne solution as preserving medium for the 
aphthae. Although we used ice and took 
other precautions, no results were obtained 
if the material took over twenty four hours 
to reach us. 
Sucking-pigs were then used for the 
transportation of virus. We found that indi 
genous pigs were the worst possibie carriers, 
but obtained good results with some half 
bred Yorkshires available near the Experi- 
ment Station. LOEFFLER also obtained good 
results with Yorkshires, though his may have 
been pure bred. 
The best way to infect them is to make 
them swallow aphthae or other contami- 
nated products, though it is advisable to 
inject or to scarify the skin if it is necessa- 
ry to obtain pustules. Another good method 


is to make the pigs suck cows that have 
contracted the disease or to give them con- 
tamined milk. 
It is exceedingly difficult to keep the 
virus in the laboratory unless sucking pigs 
are available. We could hardly get calves 
which were susceptible to the disease and 
indigenous pigs gave very uncertain results. 
On this account, we followed LOEFFLER’s 
technique or got material from neighbouring 
farms. 
Pericardial liquid aseptically taken may 
be kept for five days in 30 0/0 glycerine and 
often even for eight or ten. LOEFFLER men- - 
tions having kept it for thirty, but the long- 
est we could manage was fifteen. 
By inoculating Yorkshire pigs and with- 
drawing their pericardial liquid, we immu- 
nised a native cow which yielded a quite 
active serum. Unfortunately we had to 
abandon this method on account of the exor- 
bitant price of half-breed sucking pigs and 
the great mortality among them, especially 
as these experiments were only made so as 
to test our hypothesis. At the same time, 
other experiments were carried out on Mr. 
JOAQUIM NOGUEIRA' farm in Queluz, 
and gave very good results, thanks to the 
good-will of this landlord and the thorougness 
of our assistant JOAO CLAUDIO DE LIMA. 
The work was done in the following 
way: Aphthae taken from a bull that had had 
a virulent attack of foot and mouth disease 
were crushed in a mortar and diluted in 
phsiological solution; after that they were 
filtered, first through largemeshed tissue and 
afterwards through filtering paper. This took 
about an hour. The substance thus obtained 
was injected in the jugular vein of an ox that 
had hitherto proved refractory to aphthous 
fever. This was repeated four times, at in- 
tervals of seven days and was done at night 
so as to prevent the yirus from being spoilt 
by heat. 
Ten days days after the last injection, 
we bled the ox at the jugular vein; the 
serum obtained was kept in 0,5 0/0 carbolic 
solution. The epidemic died out on the 
