208 DISEASES OF POULTRY. 



CHAPTER XI. 



Infectious Diseases Having a Tendency to 

 Affect More than One Set of Organs. 



TUBERCULOSIS— DIPHTHERIA, DIPHTHERITIC ROUP— INFEC- 

 TIOUS LEUKEMIA — FOWL CHOLERA. 



tuberculosis. 

 /^^fc^HERE is frequent mention in medical litera- 

 / I ture of tuberculosis in birds. In Europe 

 ^^1^ this disease appears to be very cornmon, and 

 it is by no means rare in the United States, if 

 the statements of our professional men are to be 

 accepted. The observations recorded previous to 

 1884, and those made since that time, which are not 

 based upon the demonstration of the Bacillus tubercu - 

 losis, can not be accepted as perfectly reliable. There 

 are a number of diseases in which' the symptoms and 

 appearances of the diseased organs are so nearly alike 

 that a microscopical examination must be made before 

 their nature can be determined. The existence of 

 tuberculosis is determined by the presence of the germ 

 which produces it. Consequently, it is only since the 

 characters of this germ were made known that we 

 have been able to make a reliable diagnosis in sus- 

 pected cases, Koch demonstrated beyond doubt the 

 occurrence of tuberculosis in fowls, and observed that 

 the bacilli were extraordinarily abundant in the nod - 



