230 INTESTINAL BACTERIA 
and Ps. pyocyaneus were destroyed but B. tuberculosis, B. anthrax, and 
B. tetanus (spores) were not affected. Strauss and Wurtz (1889) showed 
that anthrax bacilli were killed in fifteen minutes and that the destructive 
factor in the gastric juice was the hydrochloric acid. The same con- 
clusion was reached by Kabrhel (1890). Hamburger (1890) first called 
attention to the fact that some of the acid was bound and that the free 
acid had a stronger germicidal effect. This was proven by testing the 
action of a solution of HCl with one of the same strength containing 
peptone. Kianowsky (1891) showed a direct relation between the 
number of bacteria in stomachs and the amount of acid. With patients 
possessing a faulty acid secretion many bacteria were found. Cadeac 
and Bournay (1898) found that Ps. pyocyaneus was destroyed after 
six hours and that B. anthrax and B. tuberculosis were not killed. Pet- 
tenkofer (1893) reported some startling work which was carried out in 
1893. This was done soon after the great epidemic of cholera in Ham- 
burg and Altoona. He proposed the X, Y, Z theory for cholera where 
X = bacterium; 
Y =host or soil; 
Z=environment. 
He stated that X without Y and Z would not cause cholera. So 
thoroughly did these workers believe in this theory that Pettenkofer and 
Emmerich drank pure cultures of the cholera vibrio. Each mixed 1 c.c. 
of a broth culture with 100 c.c. of 1 per cent sodium bicarbonate solution 
and drank it. Pettenkofer did not change his usual manner of living 
and, after having a diarrhoea for four days, came back to normal. 
Emmerich’s case ran a longer time. In this case the sodium bicarbonate 
neutralized the HCl of the gastric juice. The bacteria thus passed 
through the stomach and produced the usual results. 
Stern (1908) does not regard the gastric juice as such a barrier 
against bacterial invasion as some of the former workers. He regards 
persons with hyperacidity as fortunate from this standpoint, but in 
no way absolutely protected. Bile was found to decrease the bacteri- 
cidal action of the gastric juice. When proteins were present, cholera 
vibrios were found to livealong time. Pepsin was found to strengthen 
the action of the acid. Hansen (1912) infected food with B. coli and 
secured only a slight decrease of bacteria in the stomach.. Schultz- 
Schultzenstein (1908) found the gastric juice to be more germicidal 
than hydrochloric acid solution of the same strength. Gregersen (1916) 
reported some of the more recent work on this subject. He studied 
the action of the acid in the juice and whether any other factors were 
