88 THE POPULAR SCIENCE MONTHLY 



Examinations of drinking water for the agents of cholera or typhoid 

 infection is so laborious and negative results are of such uncertain value 

 that bacteriologists do not ordinarily make use of the direct isolation 

 and identification of the specific germs of the disease in determining 

 the purity of a given water, but rather look for indirect evidence of 

 pollution which may be determined with more certainty and which is 

 accordingly of greater negative as well as positive value. This evidence 

 ordinarily consists of the identification of the colon bacillus, the recog- 

 nition of which is certain and the presence of which signifies the con- 

 tamination of the drinking water with material in which the colon 

 bacillus is a normal inhabitant, namely, with human or animal waste. 

 The demonstration of colon bacilli, then, constitutes proof of pollution 

 of the water in a way that makes the introduction of cholera and typhoid 

 germs possible. Even if they are not present, the way is open for their 

 introduction at any time and the water is accordingly unfit for con- 

 sumption. 



It is desirable, it seems to me, to apply precisely the same prin- 

 ciples to money. Mr. Hilditch has demonstrated that the average num- 

 ber of bacteria in each of twenty-one bills was 142,000, while by far the 

 most common forms present were the varieties of the pyogenic staphylo- 

 coccus. These organisms were not in possession of their full virulence 

 but merely produced a more or less local reaction, on guinea-pig injection, 

 with swelling of the lymph glands of the groin. Their constant pres- 

 ence on money is certainly of greater significance than merely indi- 

 cating the exposure to the bacterial contamination of the air; they 

 clearly indicate that the money has been contaminated by handling and 

 without regard to the virulence or the danger of infection to which 

 these particular organisms themselves expose those who receive the 

 money, they establish beyond question the most fundamental and 

 significant fact for scientific demonstration, viz., that money is a 

 medium of bacterial communication from one individual to another. 



Upon the question of the communication of highly infectious organ- 

 isms, scientific evidence should now be sought by competent examina- 

 tions of money known to have been exposed to sources of such contami- 

 nation. It is not enough to know that much of the money in circulation 

 is merely dirty ; it should be known whether it is or is not a medium of 

 the transmission of disease where such disease exists to be transmitted. 

 From the contributions of Mr. Hilditch it appears that the handling of 

 money infects it; from the observations of Dr. Park it appears that 

 the germs of diphtheria and tuberculosis may live on bills infected 

 by these germs for several days or longer. It seems but a step, then, 

 to the final demonstration of the actual transmission of these and 

 similar diseases by money in circulation and to the prevention of such 

 spread of disease by the proper measures to eradicate such possibilities. 



