236 TEXT-BOOK OF BACTERIOLOGY. 



The tube may now be returned to the incubator. In fourteen 

 days afterward the beginning of development is perceptible; it has 

 reached its height after four to Ave weeks, and the cultures may 

 now be removed from the incubator and preserved at the usual 

 room temperature. Inoculation on fresh culture media is done 

 about every six weeks, thus securing transplantation of cultures 

 capable of living. 



Bacilli prosper likewise in a bouillon containing 3 to 5^ of gly- 

 cerin. Pawlowsky finally pretends to have cultivated them even 

 on potato slices prepared according to Globig's or Roux's method, 

 and protected against exsiccation by a subsequent hermetical seal- 

 ing of the test-tube. This procedure has as yet, however, not been 

 confirmed.* 



Koch succeeded, by the use of his artificial cultures in all cases, in 

 a very large series of experiments, in reproducing in susceptible ani- 

 mals typical tuberculosis with all its clinical and anatomical symp- 

 toms, and thus furnishing the valid proof of having found in the 

 bacillus the genuine sole exciter of the disease. His transmission 

 was successful in 217 animals, mostly rabbits. Guinea-pigs, and field- 

 mice. A small quantity of culture was removed by the platinum 

 needle from the surface of the culture medium, and rubbed to a thin 

 fluid by sterilized water or bouillon. Small quantities of the latter 

 introduced into the body proved invariably successful. 



Koch had caused the poisonous matter to be absorbed by sub- 

 cutaneous application, by inoculation into the interior chamber of 

 the eye, by injection into the large cavities of the body or into a 

 vein, and, finally, by inhalation, and he has evoked the outbreak of 

 tuberculosis in every way. 



Other investigators after him have proved that by our food, too, 

 containing tuberculous material, the disease can be artificially pro- 

 duced, and it is no longer to be doubted that the bacilli are capable 

 of entering the body in all possible ways. 



The changes occurring within the organism in connection with 

 tubercular infection may be generally characterized as follows : 



The disease develops in the first place in the immediate neigh- 

 borhood of the spot where the bacilli found entrance, the affection 

 being in the beginning merely local. Only later — with Guinea-pigs, 

 for instance, after several weeks—a more general infection takes 

 place gradually from spot to spot. Only when the poison from 



* The editor has seen some very flourishing pure cultures of tubercle- 

 bacilli grown on potatoes after this method in the Loomis laboratory. They 

 were prepared by Dr. J. M. Byron of this city. He has also employed this 

 method successfully himself. J. H. L. 



