388 BACTERIA IN INFECTIOUS DISEASES. 



recently dead of tuberculosis, or from the lower 

 animals, victims of spontaneous or of induced tu- 

 berculosis, were placed upon the surface of the 

 sterilized blood-serum, and the vessel containing it 

 was kept in a culture-oven maintained at a tem- 

 perature of 40 C. (104 Fahr.). During the first 

 week no marked alteration occurred, unless other 

 bacteria had gained access to the culture-medium, 

 in which case the experiment was a failure. About 

 the tenth day small points and scales became evi- 

 dent, which slowly spread, and upon microscopical 

 examination proved to consist of tubercle-bacilli. 

 After fourteen days these bacilli were used to start 

 a new culture. This was accomplished by break- 

 ing up the scales and transferring a minute quan- 

 tity to the surface of culture No. 2. After 

 transferring the bacilli in this way to several 

 successive flasks, it was assumed that the origi- 

 nal material was excluded, and that a pure cul- 

 ture had- been obtained. Inoculation of guinea-pigs 

 with these pure cultures gave rise to tuberculosis 

 with as great certainty as in those experiments in 

 which tubercular material was used. In one ex- 

 periment six newly bought guinea-pigs were ob- 

 tained. Two of these were kept as temoins, and 

 the other four were inoculated with cultivated 

 bacilli obtained in the first instance from the lung 

 of a human being who had died of military tuber- 

 culosis. In this instance five successive cultures 

 had been carried out, the time required being fifty- 

 four days. One of the inoculated guinea-pigs died 



