528 A MANUAL OF BACTERIOLOGY 



lungs, liver, spleen, kidneys and gall-bladder, bile and 

 urine, but never from the blood during life. He suggests 

 that dissemination is by the lymphatics and is probably 

 " agonal." 



The vibrio stains well with ordinary anilin dyes, 

 especially with dilute carbol-fuchsin, but is decolorised by 

 Gram's method. It is actively motile, and typically 

 possesses a single terminal flagellum at one end only, but 

 there is some variation in this respect. Spores are not 

 formed, though in old cultures Hueppe described bodies 

 which he believed to be arthrospores. In such cultures 

 the bacilli lose their regular shape, and swollen and 

 distorted involution forms are seen. 



The majority of the organisms in a young agar culture 

 assume the vibrio form, but in broth or peptone water 

 cultures two or three days old they are longer and there 

 is a tendency for them to become somewhat spirillar, but 

 regular spirals are not formed. 



Cultural characters and biology. The Koch vibrio is 

 aerobic and facultatively anaerobic, and grows well on 

 the ordinary culture media from 20 to 37 C. 



In gelatin plates at 22 C. small cream-coloured colonies 

 appear in about twenty -four hours, soon accompanied by 

 liquefaction, so that in two or three days the plate becomes 

 pitted. Microscopically, the young colonies are rounded 

 with irregular margins, cream-coloured, and coarsely 

 granular. In stab-cultures development occurs all along 

 the stab as a whitish, opaque, punctate growth, thicker 

 above than below. Liquefaction commences about the 

 second day and progresses slowly ; in the early stage 

 it is confined to the surface, and looks like a little bead or 

 air-bubble (Plate XX, 6), but in' a fortnight or so the 

 greater part of the gelatin may be liquefied. Liquefaction 

 varies greatly both in rate and in extent in different 

 cultures and stocks ; in some old laboratory cultures it 



