224 MICROBES, FERMENTS, AND MOULDS. 



that the bacillus should have so long eluded the 

 observation of the physiologists who have studied the 

 tubercle of phthisis under the microscope. The form 

 of both microbes assigns them to the genus bacillus. 



The experiments of Villemin, begun ten or twelve 

 years ago, iirst showed the parasitic nature of tuber- 

 culosis, or pulmonary phthisis. Villemin inoculated 

 rabbits with tubercular matter, showing that the 

 disease was essentially contagious. More recently 

 Toussaint and Koch have cultivated the microbe in 

 a closed vessel, and have inoculated animals with the 

 produce of the culture; all these animals died with 

 symptoms of tuberculosis. 



The still more recent researches of Cornil, as he 

 stated in May, 1883, before the Academy of Medicine, 

 have confirmed the parasitic nature of this terrible 

 disease. The microbe has been found in the giant 

 cells of the tubercle and in the sputum of consumptive 

 patients ; it has been found in the colourless corpuscles 

 of the blood, by which it is conveyed into all parts of 

 the system, and it is also found in all the organs in 

 which a tubercle can be developed. 



The bacillus of tuberculosis is somewhat smaller 

 than that of leprosy. Each bacillus is from three to 

 four micro-millimetres in length. They are generally 

 found associated in the form of chains or chaplets — at 

 any rate, this is the case in the sputum, as we see m 

 Fig. 91a. Koch has cultivated them in gelatinized 

 blood-serum. Their growth is very slow. 



