ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
349 
Bacterial Disease of Trout.* — Herren Emmerich and Weibel de- 
scribe a disease which decimated the trout in a fish-breeding establish- 
ment. At first there was loss of scales in small patches, chiefly along 
the flanks and back. In these spots small tumours appeared, and these 
at first were filled with caseous masses, but afterwards with sanious pus. 
Later on extravasations of blood could be seen beneath the skin, and 
often the surface became covered with a whitish fungoid growth. The 
animals died in from 12 to 20 days of a disease which anatomically may 
be described as a furunculosis with secondary haemorrhagic purulent 
deposits. Microscopical examination of the pustules, the deposits, the 
blood, and internal organs, showed bacilli about the length of, but 
rather thinner than the typhus bacillus, and very frequently in pairs. On 
gelatin there appeared at the room temperature in 2-3 days white points, 
which, increasing in size, pass from yellow to a brownish hue. The 
colonies lay at the bottom of little hollows. In puncture cultivations 
the colonies formed along the thrust- track in the gelatin in which later 
on a funnel was formed, together with air- bubbles ; at the bottom of 
this funnel there was a whitish bacterial sediment. In bouillon there 
was a slight deposit on the wall of the vessel ; this was easily shaken 
down, the bouillon remaining quite clear. On agar there formed a thin 
greyish-yellow deposit which later on becomes brownish. There was no 
growth on potato. The shape of the bacteria from cultures was either 
oval or long or short rods, rarely filaments. The optimum temperature 
lay between 10° and 15° C. The bacteria grew both in the presence 
and absence of oxygen. Resting forms were not observed. A 
temperature of 60° killed the cultures. The bacteria are immobile ; 
they stained well, but not with Gram. Infection experiments made by 
direct subcutaneous and intra-muscular injection, by placing the fish in 
infected water, and by mixing together healthy and diseased animals 
in the same tank, were all successful. 
Micro-organisms of Bitter Milk and Cheese, f — M. Ed. de Freu- 
denreich has described two new micro-organisms which impart a bitter 
taste to cheese. Micrococcus casei amari sp. n. was found in a bitter cheese 
made in the Canton of Berne. On gelatin it forms round pale yellow 
colonies. The gelatin is liquefied, but it does not become stringy. On 
agar it forms grey flat shining colonies with yellowish centres, bouillon 
at 35° becomes cloudy in 24 hours ; and when this medium contains sugar 
it becomes acid. On potato the growth is scanty, whitish with yellowish 
edges. It grows well in the absence of oxygen, and in the presence of 
hydrogen. It acidifies and coagulates milk, imparting to it a bitter 
flavour, which, however, is not sensibly apparent until the second day. 
Cheeses made with milk to which this organism was added were de- 
cidedly bitter. M. casei amari is very resistant to heat, desiccation, 
and disinfectants. It is not pathogenic to rabbits, and does not grow 
at low temperatures (-f- 6°), but thrives at room temperature, though 
incubation heat suits it best. In a culture four weeks old 0 • 8 per cent, 
pepton was found, and to the presence of this may be ascribed in part 
the bitter flavour ; the author, however, points out that this is insufficient 
* Arch. f. Hygiene, xxi. (1894) p. 1. 
f Ann. de Micrograpliie, vii. (1895) pp. 1-14. 
