xvi] VIBRIO AND SPIRILLUM 425 



Comma bacilli when in culture rapidly undergo degenera- 

 tion into granular de'bris ; in fact, a good deal of the white 

 deposit in gelatine and broth cultures is due to debris of 

 comma bacilli. Degeneration goes on comparatively more 

 rapidly in Agar culture than in gelatine cultures. It is a 

 notorious fact that on the surface of Agar cultures the 

 whole of the growth is found dead after from a few to several 

 months, so that no new culture can be started from such an 

 old culture. This degeneration and death occur sooner or 

 later in all cultures after the lapse of some time ; this alone 

 proves sufficiently that the comma bacilli do not form per- 

 manent seeds or spores. Koch has proved by many 

 experiments of drying that the comma bacilli are invariably 

 killed by drying, unlike spore-bearing bacilli, and at no time 

 do the comma bacilli form spores. Heating cultures (old 

 or recent) of comma bacilli to 60° to 6s° C for five minutes 

 invariably kills the cultures — proof that no spores are formed. 

 The assertion of Hueppe that the terminal granules ob- 

 served in comma bacilli are spores, viz,, arthrospores, is 

 definitely negatived by the above direct experiments. 



Comma bacilli of cholera mucus flakes or of cultures, 

 recent or old, are killed by acids, e.g., a fluid containing 

 0-2 per cent, hydrochloric acid,i so that the normal acid 

 fluid of the stomach kills the comma bacilli ; also this is 

 opposed to there being present spores in the comma bacilli. 



Comma bacilli grow well and luxuriantly between 17° 

 and 40° C, on almost anything — paste, boiled egg, turnip, 

 cucumber, cabbage, bread, meat, various fruits, &c. They 

 grow best at 35-37° C, if the medium is faintly alkaline, 

 they nevertheless grow also on neutral medium, and even 

 on some media like potato and fruit, which are slightly 

 acid. I have seen comma bacilli which, having started on 

 ' Koch, /.c; Watson Cheyne, BnL Med. Journal, 1885. 



