6 BULLETIN 662, U. S. DEPARTMENT OF AGRICULTURE 
point is strongly brought out by the opposite conclusions reached by 
the two French investigators, Jacoulet and Vigel, who found the 
disease in American horses shipped to France. The former believes 
the disease is benign, nontransmissible, and of alimentary origin, 
while the latter readily transmitted the disease to other horses and 
convinced himself of its contagiousness. 
Experiments have proved that the disease 1s most readily trans- 
missible at the time the blisters rupture or shortly thereafter, but 
when the lesions are 5 or 6 days old the virus of the disease has prac- 
tically disappeared. This may account for the greatly diifering 
results investigators have had in their attempts to ‘transfer the dis- 
ease artificially. These facts show the necessity of using several 
experiment animals for inoculation, and also of injecting the infee- 
tious material as soon as possible after the blisters have formed. 
The virus is evidently of short life. The disease usually is trans- 
mitted only by close contact, and it is probable that infected enyiron- 
ment may remain dangerous longer than the infected animal. At the 
Bureau of Animal Industry Experiment Station, at Bethesda, Md., 
a young bull was placed in close association with two cat tle in a 
pen 14 by 16 feet, 5 days after the rupture of vesicles in his mouth, 
without transferring the disease to the healthy animals. However. 
when an animal in the early stages of the disease was placed with 
these two cattle and allowed to remain until the vesicles ruptured, 
both developed the disease, one on the fourth day and the other on 
the eighth day after rupture of vesicles in the mouth of the exposing 
animal. In other experiments, horses and cattle were placed in a 
field, set aside for animals that had recovered, 3 weeks after they 
first showed symptoms of disease and a day of two less than this 
after rupture of vesicles. Healthy cattle placed with these animals 
developed no disease. Likewise, susceptible animals turned into a 
stable which 3 weeks previously, in one instance, and 16 days previ- 
ously in another, had harbored active cases of vesicular stomatitis, 
remained well. In another experiment, a heifer was tied in an 
uncleaned stall immediately after it had been vacated by an animal 
which 5 days previously was in the active stage of the disease, 
vesicles having just ruptured. In still another, a cow was similarly 
placed in a stall immediately after another cow in which vesicles 
had ruptured in her mouth 53 hours earlier had been removed. Both 
of these animals failed to contract the disease. As proof that their 
failure to do so was not because they were immune, both were later 
inoculated with virus and contracted the disease. Several instances 
have been reported in which a line fence or a board fence in a double 
corral has been sufficient to prevent transmission ot the disease from 
the infected animals on one side to the healthy animals on the other. 
Investigations indicate that the disease is very seldom communi- 
cated by owners or caretakers of affected animals visiting other 
farms. Asa rule the disease appears to spread by direct contact with 
recently affected animals, or by recently infected feed troughs, water 
troughs, bridles, or pails. However, in one outbreak, in which the 
virus seemed to be unusually virulent, the disease appeared to spread 
in some other way in addition to these, possibly by a person who 
visited infected herds and then handled susceptible cattle. In this 
a 
