160 Agricultural Bacteriology. 



causes death by suffocation. The accumulation of the 

 exudate in the cavities of the head often causes a swelling, 

 hence the common name for the disease "swell-head." 



The disease is to be differentiated from simple catarrh r 

 which closely resembles the "cold in the head" of man. 

 Simple catarrh is caused by improper ventilation of 

 houses, dampness, cold winds, and exposure. Roup is 

 often supposed to be produced by similar conditions. It 

 has been shown experimentally that it is not possible to 

 produce it by such means, although they undoubtedly 

 favor its spread when once it is started in the flock. 



Prevention and treatment. The disease is most often 

 introduced into the flock by the purchase of a bird having 

 the disease in such a mild form that no symptoms are 

 noticeable. Fowls that come from flocks in which the 

 disease is present or has been recently present should not 

 be placed with other flocks. Any bird showing an ex- 

 udate from the nostrils or eyes should be removed from 

 the flock at once. Care should be taken to avoid distri- 

 bution of infection from diseased flocks to healthy ones, 

 by means of the dirt on boots, farm implements, etc. 



The dipping of the heads of the affected birds in a 2 

 per cent solution of .potassium permanganate is said to be- 

 an aid in the treatment of the disease. 



