12 



The first experiments were conducted, to find out tuhether or not 

 Roup was an infectious disease ; and, for this purpose, 10 healthy- 

 fowls which had never been exposed to infection, were confined 

 in a cage with diseased birds ; and after varying periods of 

 time, five of the healthy birds caught the disease. Fourteen healthy 

 birds were then treated by rubbing a portion of the false membrane, 

 or putrid nasal discharge from roupy birds, upon the normal, or slightly 

 scratched, mucous membrane of the nose or eyes ; and in this way, 

 two birds were infected with typical roup. 



These experiments, therefore, show the infectious nature of the 

 disease; but the degree of infectiousness was not large. We must, how- 

 ever, remember that when fowls are kept under natural conditions 

 where they are subject to cold, etc., the infectiousness may be much 

 increased. 



Having thus shown that roup is infectious, the next step was to 

 isolate the causal micro-organism, a task of some difficulty, on account 

 of the fact that the discharge from the nose, the false membrane, etc., 

 is in close contact with, and likely to be contaminated by the air and 

 food, which always contain large numbers of bacteria that fined suit- 

 able material and favorable temperature for growth in the albuminous 

 secretions of fowl. 



Very many bacteria were isolated, but when inoculated into 

 healthy chickens, they proved to be harmless. 



In other infections, such as Fowl Cholera, etc., it is comparatively 

 easy to isolate the causal organism, because it is found in the blood 

 and organs of the diseased fowl ; but in roup we find that, as a rule, 

 the organs and blood are free from bacteria, or else if bacteria are 

 present, they are harmless. 



Without giving the results of a long- continued series of fruitless 

 examinations and experiments, made within the last four years, we 

 may nay that at length we have isolated a germ which causes roup, 

 with all its varied symptoms. To this germ we have given the name 

 Bacillus cacosnius (ill-smelling), and shall refer to it as the "roup 

 bacillus." A technical description of the germ will be given in a 

 more scientific paper at a later date. 



Chronic diseases, of which we have an excellent example in roup, 

 are notoriously hard to reproduce by the inoculation of healthy ani- 

 mals, because in most cas^s of sickness there must be, not only the 

 causal organism, but a lowering of the vital forces ; and, to get over 

 the difficulty,we used pigeons, which are easily infected, to increase 

 the virulence of the causal organism and thereby assist in the infection 

 of hens. In this wa}^ we produced roup in hens at pleasure by 

 inoculation with the roup bacillus, taken from roupy pigeons. 



The " roup bacillus " tends to penetrate the deeper layers of the 

 mucous membrane or submucous tissues. Hence cultures made from 

 swabs taken from the false membranes very rarely contain the " roup 



