338 MICRO-ORGANISMS AND DISEASE [chap. 



feeding with human sputum, tuberculosis can be produced, 

 although not all animals are equally susceptible. In most 

 cases tubercles of the spleen, in others of the spleen and 

 liver are the result ; the intensity of the process in both 

 these organs is strilcing only in a very few^ successful cases ; 

 in these cases we find both those organs enlarged and con- 

 taining numerous spherical, firm, white nodules, from the 

 size of a millet seed to that of a pea. They project over 

 the capsule when superficial. In many other cases tubercles 

 are found only in the spleen. The remarkable fact is that 

 in most instances, notwithstanding the tuberculosis going on 

 in their spleen, the animals are very fat ; when, however, 

 the liver becomes involved to a large extent, the animal is 

 found emaciated. 



In the fowl occurs natural tuberculosis, but as Koch 

 has shown {Iniernat. Med. Congress, Berlin, 1890) this 

 disease in the morphology and cultural characters of the 

 tubercle bacilli is not identical with human or bovine 

 tubercle. Mafucci {Archiv f. Hygiene und Inf. vol. xi.) 

 has more in detail described this natural tuberculosis in the 

 fowl. 



Tuberculosis can be produced in animals (guinea-pigs, 

 rabbits) by inhalation. By a spray producer tubercular matter 

 finely divided can be distributed in the air in which guinea- 

 pigs sojourn ; the majority of these will become affected with 

 general tuberculosis in the usual lapse of time, the lungs 

 being here most advanced in the tubercular process. I 

 have had guinea-pigs kept in their cages in the ventilating 

 shaft at Brompton Hospital, and have thereby produced 

 general tuberculosis in the great majority of these : caseous 

 tubercles in the lungs, in the lymph glands, spleen, liver, 

 pelvic glands, were the result ; thus proving that the air of 

 any place where tuberculous persons sojourn contains the 



