586 BACTERIOLOGY. 
many other observers have reported finding varieties of 
the comma bacillus. Only a few of these can be here 
mentioned, of which there is any certainty that they 
were derived from true cholera cases. Thus Friedreich 
has accurately described and photographed a series of 
forms which, however, vary but little from the original 
type. But more interesting than the reports of varie- 
ties are the observations of the variability of the cholera 
bacillus. Claussen, in Esmarch’s institute, isolated from 
fresh cholera stools vibrios which presented in plate 
cultures a different appearance of the colonies, which 
showed a tendency to disintegrate and having an irreg- 
ular border. The nitrosoindol reaction was absent; 
bouillon cultures were non-pathogenic to guinea-pigs, 
and stick cultures grew slowly and uncharacteristically. 
On repeated inoculation, however, a guinea-pig died 
after the injection of 1 c.c. of a bouillon culture; in 
the peritoneal exudate and even in the blood character- 
istic bacilli were found and the cultures gave the indol 
reaction. Celli and Santori, in Rome (1893), isolated 
from the stools of many typical cholera cases a vibrio 
which they called vibrio romanus, which was non-patho- 
genic for animals, gave no indol reaction, did not coag- 
ulate milk, and at 37° C. grew neither in bouillon nor 
on agar. After cultivation for nine months it gave the 
indol reaction and grew at 37° C., but was still almost 
non-pathogenic. Bordoni-Uffreduzzi and Abb culti- 
vated from a typical cholera case a short vibrio which 
liquefied gelatin very rapidly and presented an abnor- 
mal growth, and gave a yellow growth on potato, but 
which on continued cultivation became more and more 
like the cholera spirillum. Variations even greater than 
occur in these varieties of cholera spirilla are met with 
among diphtheria bacilli, 
