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Rogers, Maberly, and Verney state that the bile, which of itself may cause the 
disease (Kolle), when passed through porcelain filters is harmless, and Maberly 
adds that the residue which is left behind will give a temporary immunity 
although it will not convey rinderpest. Rogers thinks that the filtered bile will 
immunize, and Kolle believes that the residue may be infectious. Kolle used 
samples of bile which were collected on the fourth or fifth days of the disease. 
Owing to the results of these experiments, it has generally been con- 
cluded that the causative agent of rinderpest can not pass through the 
pores of the finer porcelain filters. If this be true it must be larger 
than the organism of peripneumonia and should be visible (Joest). 
Since it does not appear in the filtrate of blood which is sufficiently 
diluted with salt solution to destroy the red cells, it has been thought 
by some that it must be an intra-leucocytie organism (Nicolle and 
Adil-Bey) and therefore, for the latter reason, it would not pass through 
_the filter. 
Modes of conveyance and infection—It has already been mentioned 
that all the seeretions of a sick animal are capable of causing the disease, 
but it has also been shown by Burdon-Sanderson and Koch, that al- 
though the blood is infectious from the time of the rise in temperature, 
the secretions are not capable of transmitting rinderpest until the first 
symptoms of the disease, visible upon inspection, can be noted. This 
fact, taken in connection with the viability of the virus, at least par- 
tially indicates the commonest means of infection, as well as the most 
usual modes of conveyance. | 
For many years it has been established that the introduction of 
infected material into the body of susceptible animals, whether into 
the blood or tissues or upon the mucous membranes, especially those of 
the nose and mouth, will cause rinderpest and therefore, freshly infected 
bedding, utensils, and other implements which have been used while 
caring for cattle may be dangerous and the disease may also be conveyed 
on the hands, feet, shoes, or clothing of the attendants. The possibility 
of transmitting the infection by biting insects is also to be considered 
because the virus exists in the blood. In the case of very susceptible 
animals, a very minute amount of blood, when introduced beneath the 
skin or mucous membrane, would convey the disease. 
The length of time during which the virus may remain viable in the 
soil and in stables is not determined. We know that physical condi- 
tions promptly affect the life or activity of this virus, but we also know 
that stables or pastures may remain dangerous for long periods. The 
cause of the continuance of this infection in such instances is not 
known. Whether it be that insects are the important factor or whether 
the virus remains for a long time in an active condition in the soil is 
also not clear. This is the more curious, inasmuch as it does not show 
any evidence of maintaining its viability in laboratory media prepared 
