268 BACILLI PATHOGENIC IN MAN. 



observers, and this fact shows that the supposed pure 

 cultivations of tubercle bacilli carried out by earlier 

 authors, and not under the conditions mentioned above, 

 were not pure cultivations, but were cultivations of some 

 accidental saprophyte. 

 Experiments From these cultivations Koch has infected numerous 



on animals. . ,-,-, T 



animals, and thus completed the necessary proof. In 

 the first place he has in many cases repeated the former 

 infective experiments with tubercular tissues. For 

 example, 179 guinea-pigs, 35 rabbits, and numerous 

 other animals were inoculated with nodules from 

 miliary tuberculosis, with phthisical sputum, with pus 

 from tubercular abscesses, with the material from 

 fungous disease of joints, with scrofulous glands, with 

 lupus, and with nodules from bovine tuberculosis, and 

 in all the cases tuberculosis occurred. 



inoculation The infection occurs most easily by introducing a 

 lar sputiTm CU " little sputum into a pocket in the skin over the 

 abdomen of guinea-pigs. The wound is closed with a 

 stitch, soon heals, and usually shows no reaction. 

 After two to three weeks, however, swelling of the 

 nearest lymphatic glands occurs ; at the same time the 

 seat of inoculation becomes hard, and a nodule is 

 formed. This nodule subsequently ulcerates, and 

 becomes covered with a dry crust, under which is a 

 shallow ulcer with cheesy base. The animals become 

 thin, they have difficulty of respiration, and generally 

 die in from the fourth to the eighth week. In rabbits 

 the course of the disease after such an inoculation is not 

 so definite; it is best here to inoculate into the anterior 

 chamber of the eye. 



infection by Koch has further made numerous inoculations with 



tk>nsof tuber- pure cultivations. For this purpose animals freshly 



cie bacilh. bought were employed ; they were kept in a special 



cage, killed in the early stage of the disease, and in 



order to exclude, as far as possible, all suspicion of 



accidental tuberculosis, uninoculated control animals 



were always kept beside them. The pure cultivations 



were inoculated in a variety of ways ; in the first place 



subcutaneously. As a result, all the guinea-pigs and 



