Inoculated rabbits showed inflammation in the seat of inoculation and sometimes fibrinous peritonitis and enlarged spleen. Inoculation on the cornea produced a false membrane.

In Guinea pigs induration and ulceration occurred in the seat of inoculation but recovery followed in 14 days.

Sparrows inoculated in the pectoral muscles died in three days with yellowish necrotic tissue highly charged with bacilli.

Inoculation of the chicken by Löffler and Megnin produced a circumscribed redness which soon disappeared. On the other hand Krajewski, Colin, Loir and Ducloux seem to have inoculated chickens successfully, and Cadeac says that the cultures are infecting for sparrows, pigeons, turkeys, chickens and ducks. It rests uncertain therefore whether the pseudomembranous pharyngitis of hens is a distinct disease as alleged by Löffler and Megnin or if the chickens used by these observers were not already immune by reason of a prior attack.

Löffler’s experiments showed that dogs and rats were immune. Loir and Ducloux failed to infect cattle.

In infected dove-cots a comparative immunity is attained by the older pigeons, which continue to harbor the germ, but do not suffer materially from its presence. They however communicate it to the susceptible young in the milky secretion produced in the crop and with which they feed them, and these accordingly perish in large numbers. Thus pigeons that are themselves in fine condition become the propagators of the bacillus to the more impressible.

Sparrows and other small birds are also held to be common propagators of the germ, and if they too can secure an individual immunity and yet harbor the bacillus, their passage from yard to yard may be attended with great danger. The grains soiled by their bills and not swallowed are common media of transmission.

Loir and Ducloux found the affection transmissible between man and pigeon. The identity of the bacillus with that of genuine diphtheria in man appears to have been thoroughly disproved by the observations of Roux and Yersin.

The following differential characters have been noted:

Bacillus Diphtheriæ (Klebs-Löffler). Bacillus Diphtheriæ Columbarum
1.In gelatine cultures grows only above 23°C.1.In gelatine cultures grows at 15–17°C.
2.Kills Guinea-pig and dog.2.Guinea-pig and dog nearly immune.
3.Mice immune.3.Mice usually die with hepatic necrosis.
4.Does not grow on potatoe.4.Grows luxuriantly on potatoe.