170 CLINICAL BACTERIOLOGY. 



tendants in the emptying of bed-pans, and in the cleansing 

 of soiled linen, and transference to food from want of clean- 

 liness. In this way infection from case to case takes place, 

 as may often enough be demonstrated. The disease oc- 

 curs in epidemic distribution when a common article of food 

 is contaminated. Thus, epidemics of typhoid fever have 

 been caused by milk, by oysters obtained from infected 

 water, and more frequently by drinking-water. Repeatedly, 

 a communication between wells or sources of water-supply 

 and neighboring cesspools into which undisinfected stools 

 have been emptied has been found to be the cause of 

 typhoid epidemics. In other epidemics contamination of 

 the public water-supply by means of typhoid dejections, or 

 through the washing of infected clothes, has most proba- 

 bly taken place. 



Recently, typhoid-bacilli have been observed a number 

 of times without a direct relation to cases of typhoid fever 

 being demonstrable or even suspected. Losener found 

 bacilli that corresponded in all respects with Eberth-Gaff ky 

 bacilli in a specimen of earth obtained from an untilled 

 field, and, further, in the water-supply of Berlin obtained 

 from a conduit in his laboratory. Remlinger and Schneider, 

 using perfect methods, have recently cultivated the same 

 microorganisms from earth, dust, and water. They even 

 found them in the intestines of five individuals who had 

 never suffered from typhoid fever. Observations like these 

 are, however, exceptional, and are as yet beyond explana- 

 tion. 



In order that typhoid fever may develop, in addition to 

 the taking up of the bacilli a special predisposition on the 

 part of the individual certainly appears necessary ; or the 

 bacilli must possess especial virulence or be taken up in 

 excessive number. In general, human beings may be con- 

 sidered as not particularly susceptible to typhoid fever. The 

 requirement of an especial temporal and local predisposition 

 (elevation of the ground- water), as demanded by the theory 

 that the condition of the soil bears some relation to 

 the occurrence of typhoid fever, can no longer be sustained. 



The Occurrence of the Bacilli in Typhoid Patients. 

 The bacilli are found systematically in Pcyer's patches, the 

 mesenteric glands, the spleen, the liver, and the bone-marrow 

 of typhoid patients. They are always collected in groups 

 that frequently exhibit a relation with blood-vessels. In 



