CONTRIBUTION TO THE STUDY OF SWINE PLAGUE, ETC. 331 
cholera, and after that I shall speak of those of the infectious 
pncumoententis observed in France. To avoid confusion, I 
will repeat that it is the question of the two American forms, 
hog cholera and swine plague, differentiated by Salmon. 
BIOLOGICAL PROPERTIES OF THE MICROBES OF 
SWINE PLAGUE AND HOG CHOLERA. 
1 have found them about identical with those described by 
Smith and Salmon. 
The microbe of swine plague is a coccobacillus, very small, 
immobile, coloring at both ends with the liqueous solution of 
Loeffler blue, in its entirety with the violet of gentian and easily 
taking the aniline color used in bacteriology ; it discolors by 
the method of Gram. On plates of gelatine, the colonies ap¬ 
pear only after a few days; they are dark, reticulated in struc¬ 
ture in their mass, rounded and with more or less defined 
borders. Ensemenced in strias upon geiosis, the microbe of 
swine plague gives, after twenty-four hours, round colonies, 
well defined, of various diameters, shying by transparency 
with a strong light, very often they are united. Culture in a 
meat bouillon, as well as in alkaline peptonized water, be¬ 
comes cloudy usually in twenty-four hours; this is often 
slight and the liquid appears then opalescent. After a few 
days, a deposit takes place at the bottom of the ballon of cul¬ 
ture, and little by little the bouillon returns clear; the liquid 
is once again limpid after about three weeks ; the precipitate 
becomes manifest in shaking the ballon. There is no forma¬ 
tion of invol; the reaction with the nitrite of potash, after 
adding a few drops of sulphuric acid, has only by exception 
given a very slight coloration in old cultures, never in those 
of a few days. Culture with glucosed bouillon and addition 
of carbonate of lime has not given rise to the formation of gas. 
Repeated sowings on potatoes have not given apparent cul¬ 
tures. 1 he microbe of swine plague does not coagulate milk. 
At first sight the microbe of hog cholera is easily dis¬ 
tinguished from the preceding. It also is a coccobacillus, 
but with rather large dimensions. Its mobility, absent in 
culture on solid media, did not appear to me so evident in 
liquid cultures. I have failed to color its ciliae. 
