146 APPLIED BACTERIOLOGY 



retain its vitality for a considerable period of time, but may 

 multiply almost indefinitely. Therefore the slightest con- 

 tamination with the alvine discharges from a case of true 

 enteric fever may serve to render dangerous millions of 

 gallons of drinking water. Thus, it will be seen that the 

 virulence of typhoid-contaminated water is not necessarily 

 dependent upon the organic impurity of the water, but 

 upon the specific pollution. If this is granted, and ex- 

 perimental proof may be easily applied,* it will be ad- 

 mitted that under certain circumstances the question may 

 arise, Has the epidemic of enteric fever now in pro- 

 gress in a given community had its origin in the water- 

 supply ? 



It must be admitted that the proof of specific pollution 

 in a number of the epidemics of water-borne typhoid rests 

 on a somewhat incomplete basis, as will be seen from the 

 perusal of an interesting series of papers by Dr. E. Hart, 

 which have recently appeared in the British Medical 

 Journal.f The bacillus of typhoid fever has, however, 

 been isolated by many competent observers from water 

 that had conveyed and caused the disease. Some doubt 

 attaches to the identification of the organism by some of 

 the earlier investigators .owing to the almost constant 

 presence in the waters of other organisms so closely resem- 

 bling the typhoid bacillus that their differentiation is a 



* A drop of a broth culture of B. typhosus (twenty -four hours old) was 

 well diluted with sterile water. One c.o. of this diluted culture was added 

 to 200 CO. of the ordinary tap-water. The number of organisms was 

 then estimated by an ordinary gelatine-plate culture, when 1 c.c. of the 

 water was found to contain approximately 900,000 organisms. This 

 amount of pollution was not sufficient to raise the amount of albuminoid 

 ammonia appreciably. The tap-water previously contained only 200 

 organisms per cubic centimetre. 



t ' Water-borne Typhoid : a History Summary of the Outbreaks in 

 Great Britain and Ireland, 1858 to 1893,' by Dr. E. Hart, British 

 Medical Journal, June 15, 22, 29 ; July 6, 13, 20 ; August 17, 1895. 



