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A series of guinea pigs was inoculated with 0.5 cubic centimeter each of 
virulent rinderpest blood. Three to four days later they showed increased tem- 
perature which continued for twenty days. On the second and third days of 
the fever, blood was drawn from them and injected into Babuyanes cattle with 
the result that none of the latter sickened, although all showed a reaction. Later 
inoculation of the cattle with 5 cubic centimeters of virulent blood showed none 
to have any appreciable degree of immunity. 
The attempts to discover and isolate the organism.—In rinderpest, 
as in all other of the diseases the etiology of which is not known, many 
observers have described organisms believed by them to be the active 
cause of the infection. Thus, Metschnikoff and Gamaleia constantly 
found in the ulcers of the fourth stomach of sick animals, but not con- 
stantly in the blood, bacilli which caused symptoms of rinderpest in guinea 
pigs and calves. Simpson, Edington, Blin and Carongean, Saccharov, 
Sadowski, Konew and Trofinow, Semmer, Nencki, Sieber and Wysni- 
kiewiez, and Nencki and Sieber, have described other bacteria, but none 
of these have been proved to be the causative factor. 
The virus of rinderpest—The etiologic factor is at the present time 
unknown in spite of conscientious labors of the best workers, extending 
over a period of many years. However, it is certain that the infecting 
agent is contained in the secretions of the nasal passages, conjunctiva, 
intestines, and in the blood of infected animals, for with any one of 
these the disease can be reproduced in other individuals. ‘The most 
certain method of conveying rinderpest is by the injection of infected 
blood. In using the latter it has been said ‘that 1/500 is just as 
effectual in producing the disease as is 1 cubic centimeter and that 
with the former amount, non-immune animals may be killed. (IXKoch, 
Kolle, Turner, Nicolle, and others.) From our observations we are 
able to confirm this dosage only in the cases of cattle which may be 
called absolute non-immunes, as are the American cattle which we have 
used. With native animals even from the above-mentioned non-infected 
islands, this minimal dosage results in a variable incubation period and 
a diminished intensity of the disease. Some of these cattle, but not 
all, would probably die if infected with such a minimal dose, but in 
some instances even 0.1 cubic centimeter of virulent blood will not 
produce the disease and also the incubation time is noticeably shorter 
after a dose of 5 than after 1 cubic centimeter, vet the cattle from these 
Islands are certainly non-immunes. (See cases, Chart 5, No. 931, and 
Chart 2, No. 907.) 
The viability of the virus.—The virus of rinderpest from the blood or the 
animal secretions mentioned above possesses little viability. Left at a fairly warm 
room temperature it soon becomes inactive; it retaits its activity longer when 
it is placed on ice, but even under these circumstances the period is not very 
great. The length of time during which it may be kept in a viable condition 
varies, according to reports, between three and thirty-two days, but our experience 
