136 
FRANK S. BILLINGS. 
This object retains its virulence under artificial conditions 
much longer than either of the others. 
It is also oval, hence a bacterium. 
It colors well in the usual tinctions, but diffusely, and does not 
differentiate into two different substances as the others do. On 
account of press of work, its manner of development has not been 
studied. Contradistinctionally to the other two organisms, it 
grows well in gelatine along the whole line of puncture at once, 
the individual colonies being marked by the delicate serrated ap¬ 
pearance of the line and ends as an individual colony, the whole 
appearing like a pin upside down—(when large quantities of ma¬ 
terial are upon the wire, the S. P. organism gives about the same 
appearance in fresh gelatine). It also spreads over the exposed 
surface of the gelatine, as a delicate, lustrous, pearly gray coat¬ 
ing, with great rapidity. It generates offensive gases, or a gas, 
which frequently form globules in the substance of the gelatine. 
It does not cause the gelatine to become fluid. 
My readers will, therefore, please take notice that here are two 
organisms that bear much similarity to that of S. P. in their man¬ 
ner of development, and that all three represent three absolutely 
distinct micro-organisms, as they are each from sharply different 
diseases—clinically—though they must all be classed as u bac¬ 
teria” ; that they are oval organisms, all having much in common 
in their artificial development; that neither fluidifies the gelatine, 
yet they have essential biological points of differentiation, the 
chief of which is that they each produce different clinical and 
necroscopical phenomena. 
To this group of micro-organisms also belongs that of the Ger¬ 
man “ schweineseuche,” or swine plague, which it has been very 
hard for me to accept as identical with the American disease, but 
which recent experiences and more exact studies have about con¬ 
vinced me to be in reality the same disease. (My former posi¬ 
tion on this question can be seen by reference to the paper upon 
“ hog cholera ” read by my assistant, Dr. Thomas Bowhill, before 
the Ilinois Veterinary Association, Nov. 11, 1886, and published 
in the American Veterinary Review, December, 1886* and 
January, 1887.) My reasons for this change of opinion will be 
alluded to later on and treated in full in two papers—one upon 
