13 



bacillus," because the bacilli are retained in the depths of the animal 

 tissue. 



The " roup bacillus " is especially difficult to isolate in cases in 

 which the bird has had the disease for a long time, as the tumours 

 and false membranes contain very many other kinds of bacteria in 

 large numbers. In our experiments, even when roup was produced in 

 healthy fowl by inoculation with pure cultures of the " roup bacillus," 

 the mucous discbarge from the very beginning contained many kinds 

 bacteria. 



The roup germs seem capable of remaining in a sort of dormant 

 condition in the depths of the tissues for a long time, — so long that 

 the fowls sometimes appear convalescent ; suddenly, when the con- 

 stitution is weakened by a cold or other causes, the roup germs become 

 active and the roupy symptoms re-appear. 



We have also found that roup, with all its varying symptoms, can 

 be produced by the inoculation of healthy hens with the well-known 











Fig;. S.— The Roup bacillus (B. 

 cacosmiis), from a twenty-four 

 hour old agar culture. 



Fiji, 9 — The Roup bacillus shew- 

 ing the flagella (organs of locomo- 

 tion). Van Ermegem's method. 



Bacillus pyocyaneus, or green pus germ, which we have frequently 

 isolated from roupy birds. Hence, it would seem that roup is simply 

 a complex suppurative process ; but, different from ordinary forms of 

 suppuration, the pus in fowls appears in the form of a half or entirely 

 solid, cheese-like, yellowish white mass, without any tendency to be- 

 come soft or liquid, or to perforate the surrounding skin. 



This may be proved by the injection of sterile turpentine (oil) 

 into the eye-lids, which gives rise to inflammation and the formation 

 of solid cheese-like matter in the depth of the tumour. 



Therefore, the cheesy masses must be regarded as pus. 



To sum up, roup, or fowl diphtheria, canker, etc., is a complex 

 of suppurative processes, taking place especially in the head of fowls. 

 This suppuration may be caused by different species of bacteria, 

 and these may be very wide spread (e. g. Pyocyaneus), and thus an 

 outbreak of roup may occur in a flock living in unsanitary condi- 

 tions, without any previous introduction of the germs from elsewhere ; 

 but certainly this is the exception. More often, the disease is spread 



