344 AGRICULTURAL BACTERIOLOGY 



has been shown experimentally that it is impossible to pro- 

 duce roup in these ways. There seems to be no doubt, how- 

 ever, that birds suffering from catarrh are susceptible to 

 roup. 



Roup may be carried from flock to flock by the transfer 

 of birds with a mild form of disease. Fowls should not be 

 purchased from infected flocks, and it is well to place in 

 quarantine for some days new birds or those that have been 

 at shows before placing them with the flock. Any bird 

 showing any discharge from the mouth or eyes should be 

 removed at once from the flock. 



White diarrhea. Of the diseases affecting young chicks, 

 white diarrhea is the most important. It is probable that 

 more than one trouble has been classed under this name. 

 The white diarrhea of young chicks, caused by B. pullorum, 

 is the most important. This disease offers an example of 

 hereditary transmission of disease. It has been shown that 

 the ovaries of the hen may be affected, and that the ova 

 contain the organism. The young chick becomes infected 

 from the yolk sac. Some of the females that survive con- 

 tinue to harbor the germ and become bacillus-carriers. The 

 adult females may become infected by contact with other 

 infected adults or by infected litter. They may then be- 

 come bacillus-carriers. The infection is in all probability 

 acquired through the mouth. 



The economic importance of the disease is occasioned by 

 its effect on young chicks. The greatest danger of infec- 

 tion is during the first forty-eight hours. The danger of 

 infection is very slight after four days. 



The affected chicks appear stupid and remain under the 

 hover or hen much of the time. The feathers become rough, 

 and the wings droop. There is constant loss of weight. 

 The chicks eat little and appear unable to pick up their 

 food. A whitish discharge from the vent soon makes its 



