INFECTIONS OF THE DIGESTIVE TRACT 243 



University. 1 He ascribed to it the constitution of 

 skatol-amido-acetic acid, but it has been shown by other 

 workers that there is evidence for considering trypto- 

 phan as an isomer of skatol-amido-acetic acid; namely, 

 indol-amido-propionic acid. 



It has been known since the days of Claude Bernard 

 that tryptophan arises at an early period in the putre- 

 faction of proteids. It was further observed that while 

 the tryptophan color reaction is almost always observed 

 in the early stage of putrefaction, it later disappears. 

 The cause of this disappearance is the further cleaving 

 action of bacteria or unorganized ferments. Hopkins 

 was able to show that the action of bacteria upon trypto- 

 phan may lead to the formation of indol, skatol, indol- 

 acetic acid, and indol-propionic acid. An endeavor was 

 made to determine the influence of individual types of 

 bacteria upon the cleavage of tryptophan, and it was 

 found that B. coli is capable of giving rise to considerable 

 yields of indol at the same time that it produces indol- 

 acetic acid. Observations with cultures of symptomatic 

 anthrax representing a typical spore-bearing anaerobe, 

 showed that this organism is able to make indol-propionic 

 acid. At present, however, there is no evidence that 

 more than a small proportion of tryptophan in a medium 

 is converted into indol through the action of putrefactive 

 anaerobes. I studied many years ago the influence 



1 Hopkins, F. Gowland, and Sydney W. Cole, "Contributions 

 to the Chemistry of Proteids," Ft. II, "The Constitution of Tryp- 

 tophane and the Action of Bacteria upon It," Journ. of Physiol., 

 xxix, p. 451, 1903. 



