XL] BACILLUS : PATHOGENIC FORMS. 167 



points and streaks, which by and by become confluent and 

 caseous ; tuberculosis of the peritoneum ; isolated tubercles 

 in the lungs, at first grey and transparent, then caseating in 

 the centre ; enlargement and subsequent caseation of the 

 bronchial glands. 



Owing to the fact that the tubercle-bacilli require for their growth 

 high temperatures (37 to 39 C.), it is evident that, unlike some other 

 pathogenic organisms, they do not thrive in the outside world in 

 temperate climates. 



Inoculation with the pure bacilli into the anterior chamber 

 of the eye of rabbits and guinea-pigs produces the character- 

 istic tuberculosis described by Cohnheim and Salomonsen. 

 After an incubation oifrom two to three weeks there appears 

 on the iris a crop of minute grey tubercles enlarging and 

 undergoing caseous degeneration. Later on general tubercu- 

 losis of the eyeball and other organs follows. So that Cohn- 

 heim's assertion, that only tuberculous matter implanted into 

 the anterior chamber of the eye can produce this outbreak of 

 a crop of tubercles on the iris, is, by Koch's observations, 

 strengthened in the highest degree; the tubercle-bacilli 

 present in, and characteristic of, true tubercles are thus 

 manifestly connected with the real cause of the morbid growth. 

 A large number of pathologists have, since the publication 

 of Koch's paper, devoted themselves to various parts of 

 this question of the relationship of the tubercle-bacilli 

 to the tuberculous process, and have, with few exceptions, 

 verified Koch's observations. The chief opposition, 

 leaving out of account those who, either from imperfect 

 technical skill in the manipulation and staining of the 

 bacilli, or by reason of the inadequate number of their 

 observations, have denied Koch's statements, comes mainly 

 from observers who, like Toussaint, Klebs, and Schiiller, 

 maintain that tuberculosis is due to a micro-organism which 



