196 BACTEKIA. 



city, and the tides sweep this refuse up as well as down 

 the river, and some of it gets into the filter beds. Would 

 you prefer to drink an infinitesimal quantity of sewage 

 with the whole of the noble Hudson as a diluent, or to 

 drink cistern water collected from roofs and containing 

 a large proportion of the excreta of birds, and all the 

 unutterable abominations of street dust, tubercle and 

 typhoid bacilli perhaps included, with the bodies of in- 

 sects and slugs for variety — the whole mixture standing 

 stagnant in the dark for weeks before it is used ? You 

 have your choice. 



A chemical examination does not help us in this mat- 

 ter, but there is one way to determine whether water is 

 fit to drink or not, and this is the way to do it : A num- 

 ber of tubes of bouillon are carefully sterilized and to 

 each one is added a cubic centimetre or thereabouts of 

 the water to be examined. The tubes are then put in 

 the brood oven and kept at 100° for twenty-four hours. 

 They are then found to be turbid from the growth of 

 bacteria. The cultures are mixed together in a sterilized 

 bottle and some of the mixture is injected under the skin 

 of a rabbit. If no harm comes to the rabbit the water is 

 pronounced fit to drink. It is axiomatic that microbes 

 which will not grow at the body temperature can do no 

 possible harm if introduced into the system. With the 

 assistance and careful and able co-operation of Dr. John 

 Faust, the veterinary surgeon, I made injections of such 

 cultures into three healthy rabbits on the tenth of Janu- 

 ary last. Dr. Faust kept a record of the temperature of 

 the animals and watched carefully for symptoms of local 

 or general disease. With the exception of a very slight 

 rise of temperature immediately following the injections, 

 and probably due to the foreign matter so suddenly in- 

 troduced into their systems, no harm whatever resulted 

 to the animals; the same experiment was repeated on 

 March ninth on two other rabbits with the same result; 



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