222 DISKASES OF POULTRY. 



predispose the birds to the disease. It is, however, 

 very doubtful if the disease can be originated by such 

 conditions in the absence of direct infection from 

 affected birds. 



Bacteriological investigations made by Loeffler, 

 Loir and Ducloux, and Moore indicate that the 

 diphtheria of birds is caused by a non- motile bacillus 

 0.8 to 1.5 micro -millimeters long by 0.8 to 1.2 micro - 

 millimeters broad, resembling somewhat the bacillus 

 of fowl cholera, and rabbit septicaemia. There are 

 slight differences in the descriptions given by these 

 investigators — differences which may be accounted for 

 by variations of the germs under dissimilar conditions. 

 All who have carefully studied the bacillus agree in 

 the conclusion that it is entirely distinct from human 

 diphtheria and that these diseases have only superficial 

 points of resemblance. It has been found, however, 

 that a form of diphtheritic sore throat sometimes 

 occurs in people who are working about birds affected 

 with diphtheria ; but this disease differs radically from 

 the ordinary human diphtheria and is much less 

 serious. There are recorded cases, moreover, in 

 which it appears that the diphtheria of children has 

 been communicated to birds and the contagion 

 preserved for a considerable time in that manner. 

 It may be that some of the cases of fatal disease 

 in children contracted from fowls were caused 

 by the contagion of the human form of the disease 

 preserved in this way. 



There are probably several distinct diseases which 

 have been and are generally confounded together as 

 diphtheria or diphtheritic roup. A disease of the na- 

 ture of croupous angina has been described in pullets 

 and young pigeons by Rivolta and D.-lprato aad also 



