Pathogenicity. 427 



Both pox and diphtheria are easily transmitted from 

 chickens -to chickens and from pigeons to chickens, whereas 

 the transfer of pox material from chickens to pigeons is ac- 

 complished with difficulty, and transmission of diphtheria ma- 

 terial has thns 2-dv been unsuccessful. The infective virus trans- 

 ferred from the pigeon to the chicken appears to undergo an 

 attenuation even in the first generation ; but also in the pigeon 

 the virus becomes attenuated by successive passages even to 

 avirulency (Juliusberg). 



Aside from its presence in the epithelial nodules and 

 mucous meml)ranes the virus is also found in the blood, at 

 least in the beginning of the disease, for it was repeatedly 

 found possible to produce the characteristic changes on skin 

 and mucous membrane, especially with liver substance (Loew^en- 

 thal, Burnet, Schmid, Uhlenhut'h & Manteufel). 



The above mentioned experimental results permit the con- 

 clusions, that epithelial nodes and diphtheritic pseudo-mem- 

 branes contain the same virus which produces pox on the skin 

 and diphtheritic processes on mucous membranes, and therefore 

 chicken pox and avian diphtheria form an etiological entity. 

 This view is supported by an experimental result obtained by 

 Uhlenhuth & Manteufel, according to which recovery from the 

 affection of the mucous membrane produced with diphtheria 

 material gives immunity against a subsequent artificial skin 

 infection with virulent pox virus. 



In consideration of the present viewpoint the question arises what 

 significance attaches to the more or less pathogenic bacteria found by 

 different authors in the diphtheritic pseudo-membranes and considered 

 by them as causes of the disease on account of the partly successful 

 experiments of transmission. The following come under consideration : 



1. The bacillus diphtheriae cohimbanini obtained in pure culture by Loeffler 

 from a case of pigeon diphtheria. This bacillus, which takes a bipolar stain, is similar 

 to the organism causing rabbit septicemia, but slightly longer and more slender; 

 its pure cultures, after subcutaneous inoculation, produce in pigeons a necrotic 

 inflammation of the skin, while after injection into the oral mucosa of chickens 

 circumscribed pseudo-membranes form. Loir & Ducloux no doubt found the same 

 bacillus in diphtheritic chickens in Tunis, only this organism was characterized by a 

 marked virulence, while its cultures after subcutaneous inoculation soon produced a 

 rapidly fatal septicemia, or heavy deposits in the throat and in the larynx in addi- 

 tion to general septic symptoms. 



2. The "Eoupbacillus," an organism in many ways similar to the bacillus 

 pyocyaneus, described by Streit as the causative factor of American "roup," a 

 disease clinically identical with chicken diphtheria. He found it in abundance 

 in the disease products of sick birds and made with his pure cultures experiments of 

 transmission to chickens and pigeons, which were in part successful. 



3. The "Chiekendiphtheriabacillus" of E. Miiller, which he describes as 

 related to the human diphtheria organism or Loeffler 's bacillus, although a smaller 

 corynebacillus. He obtained pure cultures which upon inoculation in mucous mem- 

 branes or injection into the submucosa in pigeons produced a diphtheritic inflam- 

 mation. 



4. A colon-like bacillus, which Hausser was enabled to constantly demonstrate 

 in spontaneous diphtheria in the deposits, and with whose pure cultures he succeeded 

 several times in producing a diphtheritic inflammation in chickens and pigeons. 



Finally there may be found in the diphtheritic deposits in some cases the 

 bacillus pyocyaneus, streptococci, chicken cholera bacteria, necrosis bacilli and some- 

 times swine erysipelas bacilli. 



