414 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
somewhat the growth and the human body temperature arrests it entirely and the 
organism is killed by an exposure to it of seventeen hours. The thermal death point 
is therefore low. For bouillon cultures it lies between 42° C. and 43° C. during an 
exposure of ten minutes. 
Viability on media . — A culture on a sealed agar slant was still alive at the end of 
seven months. Upon transfer, however, it grew more slowly than ordinary cultures, 
and the pigment did not appear until between the sixth and tenth day. On the 
second transfer growth and chromogenic property were restored substantially to the 
normal. 
Relation to free oxygen . — Agar plates in vacuo, by exhaustion with a Chapman 
pump and absorption by pyrogallic acid and caustic potash, show after two days very 
small microscopic colonies, while agar slants show a slight growth, neither of which 
increase after several days. No color appears. This incipient growth is probably 
due to incomplete absorption of oxygen at the beginning of the experiment, and the 
organism is probably an obligate aerobe. 
Fermentation tests and products of growth . — It does not ferment the carbohy- 
drates glucose, lactose, or saccharose. Cultures in 1 per cent glucose bouillon acquire 
an acidity, or an increase of acidity, of 1.2 per cent to 1.6 per cent in fifteen days, due 
probably to acetic acid, and the characteristic brown color is not developed. Lactose 
and saccharose bouillon show only a slight or no development of acidity, while the 
pigment production takes place much as in plain bouillon. The acidity apparently 
breaks up or prevents the formation of the pigment. 
It reduces nitrates to nitrites and finally to ammonia. Seven-day cultures in 
nitrate broth contain both nitrites and ammonia. Forty-day cultures contain no 
nitrite, but give a strong test for ammonia. It does not produce indol, phenol, 
ammonia, invertin or cliastatic ferments. 
The characteristic pigment is produced in agar, bouillon, Dunham’s pepton 
solution, and blood serum, but not in gelatin or upon potato. It is produced in 
alkaline, neutral, and acid media, and is inhibited by extremes of reaction, as the 
growth itself of the organism is inhibited. The pigment is soluble in alcohol* and 
colors the nutrient medium instead of the bacteria themselves, though ivith age the 
latter take on a shade of the color of the pigment. In liquid media and in crowded 
agar plates it colors uniformly the whole media, while in agar tubes the diffusion is 
slower, the part nearest the growth having the deepest color. It is produced at the 
room temperature. Higher temperatures inhibit the color faster than they do the 
growth. At 314° 0., which retards slightly the growth, the color is entirely 
inhibited, at least for a space of four days. In agar tubes the color appears on the 
third day, on blood serum after three or four days, in bouillon after two weeks, and 
in Dunham’s pepton solution after three weeks. 
Cultures do not have a marked odor. 
Motility . — The organism direct from the blood or local lesions of the trout gives 
no sign of motility in the hanging drop, and its conduct in liquid media when recently 
isolated — a sedimenting growth without clouding — indicates nonmotility; but after 
it has remained for several months on artificial media and been repeatedly transferred 
a change takes place in its appearance in hanging drop and in its growth in bouillon. 
a Dr. C. L. Alsbers. Harvard Medical School. 
