BACTERIA AND DISEASE 285 



tuberculous cattle would succeed in transmitting tubercu- 

 losis to some sheep. 



Tuberculosis in the horse is relatively very rare. It attacks 

 the organs of the abdominal cavity, especially the glands; 

 it affects the lung secondarily as a rule. The cases are gen- 

 erally isolated ones, even though the animal belongs to a 

 stud. Nocard holds that the bacillus obtained from the 

 pulmonary variety is like the human type, whilst the ab- 

 dominal variety is more like the avian bacillus. 



Nocard says 1 : 



" If the dog can become tuberculous from contact with man, 

 the converse is equally true. Infection is at any rate possible 

 when a house-dog scatters on the floor, carpet, or bed, during 

 its fit of coughing, virulent material, which is rendered extremely 

 dangerous by drying, especially for children, its habitual play- 

 mates. The most elementary prudence would recommend the 

 banishment from a room of every dog which coughs frequently, 

 even though it only seems to be suffering from some common* 

 affection of the bronchi or lung." 



Tuberculosis is a common disease among the birds of the 

 poultry-yard: poultry, pigeons, turkeys, pea-fowl, guinea- 

 fowl, etc. They are infected almost exclusively through 

 the digestive tract, generally by devouring infected secre- 

 tions of previous tubercular fowls, Whatever the position 

 or form of avian tuberculosis, the bacilli are present in 

 enormous numbers, and are often much shorter and some- 

 times much longer than those met with in tuberculous 

 mammalia, and grow outside the body at a higher temper- 

 ature (43 C.). They are also said to be more resistant and 

 of quicker growth. The species is probably identical with 

 Koch's bacillus, though there are differences. In the nodule, 

 which is larger than in human tuberculosis, there are few or 

 no giant cells, and it does not so readily break down. 



1 Animal Tuberculosis, p. 129. 



