﻿IX, B, 1 Boynton: Cultivatio7i of Virus of Rmdei-pest 43 



found to be approximately 34832921 cubic centimeter. From the 

 experiments quoted above it was found that %060 and 0.0001 

 cubic centimeter of fresh virulent blood failed to transmit the 

 disease. Therefore, it appears that there was a multiplication 

 of the virus in the culture tubes, since the dilution of the original 

 virulent blood that resulted from the successive transfers was 

 so much greater than the quantity which was found necessary 

 to produce the disease. In one series I was not able to reproduce 

 the disease from the medium first inoculated after twelve days, 

 but the fourth transfer corresponding to a period of twelve days 

 after removal from the sick animal proved virulent. This would 

 suggest that the virus continued to live in the transfers, but 

 died out, or lost its virulence, in the original tube of culture 

 medium. 



In the salt-peptone medium myriads of minute bodies could 

 be seen under dark field illumination, especially in transfers of 

 the first and second generations. A large number of check 

 examinations have been made with normal blood. In some 

 instances bodies practically identical with those found in cultures 

 made from virulent blood are found. Therefore, at present, 

 nothing can be stated concerning the morphology of the etio- 

 logical factor. In the salt-peptone medium there appears a per- 

 ceptible cloudiness above the blood on the bottom of the tube. 



Up to the present time the best results have been obtained by 

 taking blood from an animal in the early stages of the disease; 

 that is, about the second day of temperature. All animals em- 

 ployed to test the existence of rinderpest virus in culture media 

 were kept under such conditions as to warrant the belief that 

 no accidental infection occurred to cause fallacious conclusions. 



The greatest precaution must be taken against contamination, 

 since the media are composed chiefly of raw blood which cannot 

 be sterilized. I have twice lost the seventh transfer on account 

 of bacterial contamination, which appears to kill the virus in 

 a very short time. The presence of contaminative bacteria is 

 usually revealed by a pellicile immediately beneath the paraffin 

 oil. 



One animal which was inoculated with the fourth transfer 

 recovered from the disease. This animal is at present being 

 hyperimmunized with cultures, with the intention, in the near 

 future, of testing the potency of its serum as compared with 

 serum from animals immunized with virulent blood. Experi- 

 ments are being carried on to determine if it is possible to 

 produce a toxin in culture and to prepare an antitoxin. Work 



