600 PATHOGENIC SPIRILLA. 
present in vomited matters, but Koch found it in small numbers in 
two cases and Nicati and Rietsch in three. In about one hundred 
cases in which Koch examined the excreta, or the contents of the in- 
testine of recent cadavers, during his stay in Egypt, in India, and in 
Toulon, his ‘‘ comma bacillus” was constantly found, and other ob- 
servers have fully confirmed him in this particular—Nicati and 
Rietsch in thirty-one cases examined at Marseilles ; Pfeiffer, twelve 
_ cases in Paris; Schottelius in cases examined in Turin; Ceci in 
Genoa, etc. On the other hand, very numerous control experiments 
made by Koch and others show that it is not present in the alvine 
discharges of healthy persons or in the contents of the intestine of 
those who die from other diseases. In the writer’s extended bacte- 
riological studies of the excreta, and contents of the intestine of ca- 
davers, in’ yellow fever, he has not once encountered any microér- 
ganism resembling the cholera.spirillum. 
As none of the lower animals are liable to contract cholera during 
the prevalence of an epidemic, or as a result of the ingestion of food 
contaminated with choleraic excreta, we have no reason to expect 
that pure cultures of the spirillum introduced by subcutaneous inocu- 
lation or by the mouth will give rise in them to a typical attack of 
cholera. Moreover, it has been shown by experiment that this spi- 
rillum is very sensitive to the action of acids, and is quickly de- 
stroyed by the acid secretions of the stomach, of man or the lower 
animals, when the functions of this organ are normally performed. 
By a special method of procedure, however, Nicati and Rietsch, and 
Koch, have succeeded in producing in guinea-pigs choleraic symp- 
toms and death. The first-named investigators injected cultures of 
the spirillum into the duodenum, after first ligating the biliary duct; 
the animals experimented upon died, and the intestinal contents con- 
tained the spirillum in large numbers. The fact that this procedure 
involves a serious operation which alone might be fatal, detracts 
from the value of the results obtained. Koch’s experiments on 
guinea-pigs are more satisfactory, and, having been fully controlled 
by comparative experiments, show that the ‘‘comma bacillus” is 
pathogenic for these animals when introduced in a living condition 
into the intestine. This was accomplished by first neutralizing the 
contents of the stomach with a solution of carbonate of toda—five 
cubic centimetres of a five-per-cent solution, injected into the stomach 
through a pharyngeal catheter. For the purpose of restraining in- 
testinal peristalsis the animal also receives, in the cavity of the abdo- 
men, a tolerably large dose of laudanum—one gramme tincture of 
opium to two hundred grammes of body weight. The animals are 
completely narcotized by this dose for about half an hour, but re- 
cover from it without showing any ill effects. Soon after the ad- 
