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 recognition of which is certain and the presence of which signifies the contamination 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 consumption.
It is desirable, it seems to me, to apply precisely the same principles to money. Mr. Hilditch has demonstrated that the average number 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 staphylococcus. 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 presence on money is certainly of greater significance than merely indicating 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 organisms, scientific evidence should now be sought by competent examinations of money known to have been exposed to sources of such contamination. 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.
