4 MASS. EXPERIMENT STATION BULLETIN 311 



visible effect upon the mucous membrane of either the cloaca or the bursa of 

 Fabricius. In these cases, the mucous membrane was inflamed from rubbing, 

 but the inflammation was transient and the mucous membrane was dry, indicating 

 that the condition was due to the mechanical destruction of the epithelium which 

 kept the surface moist. To the pathologist this is known as desquamative 

 inflammation, and it was so called in this experiment. 



A poor take was indicated in those cases in which the mucous membrane of 

 the cloaca or bursa of Fabricius, or both, was moist from the exudation of mucous 

 and serous fluids. Sometimes the feathers around the vent were moist and soiled. 

 This was called serous inflammation. 



A fair take resulted when the exudate was fibrinous and the mucous membrane 

 showed petechial hemorrhages in the bursal groove and the opening into the 

 bursa of Fabricius. This was designated as fibrinous inflammation. 



A good take showed all of the characteristics of a fair take plus a diphtheritic 

 plug in the opening into the bursa of Fabricius and ecchymosis of the mucous 

 membrane of the bursal groove. This is mild diphtheritic inflammation, and a 

 good take differed from an excellent take only in the severity of the inflammation. 



An excellent take showed not only a diphtheritic plug in the opening into the 

 bursa of Fabricius, but pseudomembrane on the mucous membrane of the bursal 

 groove similar to that occurring in the larynx and trachea of birds suffering from 

 natural infections. Sometimes hyperemia and hemorrhage of the mucous 

 membrane of the bursal groove and bursa of Fabricius were evident. This 

 condition would be designated by pathologists either as severe diphtheritic or 

 as hemorrhagic inflammation depending upon the condition most evident. 



It should be noted that most of the excellent takes occurred in the pullets 

 and cockerels 4-7 months old and that the chickens 1-3 months old were second, 

 while the hens and roosters 8-12 months old were third. This indicates that, 

 under the conditions of the experiment, the best time to vaccinate is between 

 4 and 7 months of age. 



Table 1. The Number of Days After Vaccination in Which 

 Takes were Evident. 



