224 MICROBES, FERMENT'S, 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, first 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 in 
Fig. 914. Koch has cultivated them in gelatinized 
blood-serum. Their growth is very slow. 
