INVESTIGATIONS OF THE BUREAU OF ANIMAL INDUSTRY. 629 
Schiveineseuche germ, the latter says it is caused by the hog 
cholera germ. Billings says there is no disease produced by 
the hog cholera germ in the United States—Frosch says there 
is none caused by the swine plague germ. This certainly is 
one of the mose remarkable endorsements on record. 
With this condition of affairs before us, we must inquire 
whether it is not possible that Billings had the hog cholera 
germ in his cultures previous to 1889 as well as after that date. 
Do not these germs resemble each other so closely that a bac¬ 
teriologist might be excused for thinking he had one when he 
really had the other? So far from this being the case, these 
two germs are radically different, and any bacteriologist 
who confessed his inability to distinguish between them after 
studying them for two years would certainly lose his reputa¬ 
tion. 
Frosch finds no difficulty in pointing out the most radical 
differences, although he evidently tries to let his friend Bil¬ 
lings- down as easily as possible. He shows that the hog 
cholera bacterium is motile and bears flagella, while the swine 
plague bacterium has no power of movement and no flagella ; 
the former grows at the extremes of temperature of 8° C. 
and 42 0 C., the latter has no growth at either of these ex¬ 
tremes ; the growth of the latter upon gelatine and blood 
serum is much finer, more delicate and more clinging ; the 
former in liquid cultures forms in twenty-four hours an equal 
turbidity and later a sediment, while with the latter there is 
only a slow growth found upon the bottom of the tube always 
in flakes adhering to each other ; in gelatine the colonies along 
the needle track with the swine plague bacterium are much 
finer and the surface growth more delicate, and on plates the 
colonies do not reach half the size of hog cholera ; the swine 
plague only grew on potato when the latter was alkaline, and 
as it is usual for boiled potatoes to have an acid reaction, the 
germ would not grow upon them while the hog cholera grew 
abundantly when they were acid; the hog cholera growth on 
potato was always luxuriant, and of a dirty, light-yellow color, 
that of swine plague (on alkaline potato) formed flat, not very 
extensive, gray *or yellowish-gray fields. The hog cholera 
