on account of their somewhat close resemblance to the membrane which 

 is formed in human diphtheria, it has been thought by some writers 

 that the avian and human diseases are the same. Here, how^ever, let 

 it suffice to say that the weight of evidence is against this contention; 

 but this phase of the subject will be more fully dealt with later on in 

 this'bulletin. 



We may also point out that many poultry keepers who notice the 

 false membrane on the throat and mouth of their fowls, regard the 

 disease as quite different from the catarrhal form and call it "canker", 

 which is probably a popular form of the word " cancer". 



Whether the di.sease is characterized by false membranes, offen- 

 sive discharge, or cheesy masses, the cause is the same, as we have 

 many times experimentally demonstrated. 



Fig. 4.— Hen 47 ; sixty-seven days after inoculation with B. pyocvaneus and the 

 dav before death. 



At one or several places in the mouth or throat, these yellowish, 

 smooth or uneven membranes appear, and either remain small and 

 disappear after a few days, or gi-ow thicker, spread, and become firmly 

 attached to the mucous membrane ; and if they (the false membranes) 

 are removed, an uneven, bleeding surface is exposed, which looks like 

 a true cancer. 



After the appearance of the membranes, the adjacent submucous 

 tissue sometimes becomes inflamed, and finally the growths are found 

 to be similar to those so often seen at the side of the face, — containing 

 solid cheesy matter in the centre. 



When the throat is blocked by these false membranes, the ani- 

 mal's breathing becomes abnormal, and the air passing through the 

 throat produces loud noises. Gradually, the visible mucous membrane 

 and the comb turn blue, and the fowl finally dies from suffocation. 



