CHAPTER XXXIII. 
SPIRILLUM CHOLERH ASIATICA (KOCH’S COMMA 
BACILLUS OF ASIATIC CHOLERA). 
In 1883, Koch separated a characteristically curved 
organism from the dejecta and intestines of cholera 
patients—the so-called ‘‘ comma bacillus.’’? This he 
declared to be absent from the stools and intestinal con- 
tents of healthy persons and of persons suffering from 
other affections. The organism was said to possess cer- 
tain morphological and biological features which readily 
distinguished it from all previously described organisms. 
Tt was absent from the blood and viscera, and was found 
only in the intestines; and in greater number, it was 
said, the more acute the attack. Koch also demonstrated 
an invasion of the mucosa and its glands by the comma 
bacilli. The organisms were found in the stools on 
staining the mucous flakes or the fluid with methylene- 
blue or fuchsin, and sometimes alone; by means of cul- 
tivation on gelatin they were readily separated from the 
stools. During his stay in India, in Egypt, and at Tou- 
lon, Koch had examined over one hundred cases, and 
other investigators confirmed his statements. Numer- 
ous control observations made upon other diarrheic de- 
jecta and upon normal stools were negative; the comma 
bacillus was found in choleraic material only, or in mate- 
rial contaminated by cholera. Soon other observers, 
however, described comma-shaped organisms of non- 
