618 BACTERIA IN INFECTIOUS DISEASES. 



and in the pathological and biological laboratories of the Johns Hopkins 

 University during the winters of 1888 and 1889. 



Forty-two autopsies were made in typical cases of yellow fever and seven- 

 teen autopsies in other diseases for comparative researches. 



Aerobic and anaerobic cultures were made from the blood, the liver, the 

 kidney, the urine, the stomach, and the intestine. 



The experimental data recorded in this report show that: 



The specific infectious agent in yellow fever has not been demonstrated. 



The most approved bacteriological methods fail to demonstrate the con- 

 stant presence of any particular microorganism in the blood and tissues of 

 yellow-fever cadavers. 



The microorganisms which are sometimes obtained in cultures from the 

 blood and tissues are present in comparatively small numbers ; and the one 

 most frequently found (Bacterium coli commune) is present in the intestine 

 of healthy individuals, and consequently its occasional presence cannot have 

 any etiological import. 



A few scattered bacilli are present in the liver, and probably in other or- 

 gans, at the moment of death. This is shown by preserving portions of 

 liver, obtained at a recent autopsy, in an antiseptic wrapping. 



At the end of twenty-four to forty-eight hours the interior of a piece of 

 liver so preserved contains a large number of bacilli of various species, the 

 most abundant being those heretofore mentioned as occasionally found in 

 fresh liver tissue, viz. , Bacterium coli commune and Bacillus cadaveris. 



Blood, urine, and crushed liver tissue obtained from a recent autopsy are 

 not pathogenic in moderate amounts for rabbits or guinea-pigs. 



Liver tissue preserved in an antiseptic wrapping at a temperature of 28 

 to 30 C., for forty eight hours, is very pathogenic for guinea-pigs when in- 

 jected subcutaneous! y. 



This pathogenic power appears to be due to the microorganisms present 

 and to the toxic products developed as a result of their growth. It is not 

 peculiar to yellow fever, inasmuch as material preserved in the same way 

 at comparative autopsies, in which death resulted from accident or other 

 diseases, has given a similar result. 



Having failed to demonstrate the presence of a specific "germ" in the 

 blood and tissues, it seems probable that it is to be found in the alimentary 

 canal, as is the case in cholera. But the extended researches made, and re- 

 corded in the present report, show that the contents of the intestines of yel- 

 low-fever cases contain a great variety of bacilli, and not a nearly pure cul- 

 ture of a single species, as is the case in recent and typical cases of cholera. 



Comparatively few liquefying bacilli are found in the faeces discharged 

 during life, or in the intestinal contents collected soon after death from yel- 

 low-fever cadavers. On the other hand, non-liquefying bacilli are very 

 abundant. 



The one most constantly and abundantly present is the Bacterium coli 

 commune of Escherich. 



This is associated with various other bacilli, some of which are strict 

 anaerobics and some facultative anaerobics. 



Among the facultative anaerobics is one my Bacillus X which has been 

 isolated by the culture method in a considerable number of cases and may 

 have been present in all. This bacillus has not been encountered in the 

 comparative experiments made. It is very pathogenic for rabbits when in- 

 jected into the cavity of the abdomen. 



It is possible that this bacillus is concerned in the etiology of yellow fever, 

 but no satisfactory evidence that this is the case has been obtained by experi- 

 ments on the lower animals, and it has not been found in such numbers as 

 to warrant the inference that it is the veritable infectious agent. 



All other microorganisms obtained in pure cultures from yellow-fever 

 cadavers appear to be excluded, either by having been identified with known 

 species, or by having been found in comparative researches made outside of 



