128 THE MICHIGAN ACADEMY OP SCIENCE. 



THE VIABILITY OF THE TYPHOID BACILLUS IN SEWAGE. 



JOHN RALSTON WILLIAMS. 



In the range of sanitary science there is probably no more important 

 problem than the purification of sewage. The series of experiments 

 described in this paper were undertaken to ascertain, so far as possible, 

 the influence which typhoid germs encounter,, when discharged into a 

 sewerage system or river. Most sanitarians are agreed that they are 

 destroyed and assign various reasons therefor. Of these, perhaps the 

 most oft mentioned factor is that the saprophytic organisms present, 

 consume the food of, and thus make life impossible for the less resist- 

 ant pathogens. Other frequently assigned causes are the aeration, di- 

 lution, exposure to sunlight, etc., to which sewage is subjected when 

 poured into a floating body of water. It is not the purpose of the writer 

 at this time to consider exhaustively all of the factors concerned in the 

 bacterial purification of sewage, but rather to briefly describe some labor- 

 atory experiments, now under way, in which the endeavor is being made 

 to learn the effects on the typhoid bacillus of the competing saprophytic 

 organisms, dilution by tap .water, sunlight, etc. 



The sewage was obtained from a manhole at the outlet of the Ann 

 Arbor sewerage system. It was cloudy in appearance, had an odor not 

 particularly offensive, was neutral in reaction and contained a small 

 amount of floating matter. On the date when the sample was taken, the 

 sew-ers were discharging much surface water since a thaw of several days 

 was in progress. It was brought at once to the laboratory and plated 

 on agar for purposes of enumeration. One series of plates were grown 

 at twenty degrees C. and another at thirty-seven degrees C. The colo- 

 nies which developed thereon were counted on the three succeeding 

 days. The following experiments were then undertaken: 



Experiment I. A study of the bacterial flora of the sewage. 



Experiment II. Into about 1,500 c.c. of the sewage was poured 

 about six c.c. of a twenty-four hour beef-tea culture of the typhoid 

 bacillus. After thoroughly mixing, a beef-tea culture of this was made 

 and placed in the incubator. A culture was also made of the uncon- 

 taminated sewage as a control. This was likewise incubated. After 

 forty-eight hours growth one c.c. and two c.c. respectively of each cul- 

 ture"^ were injected intraperitoneally into guinea-pigs. The pigs which 

 received the two c.c. died within eighteen hours. A postmortem exam- 

 ination of each showed the peritoneum, mesentery, kidneys and adrenals 

 considerably congested, while the spleen was markedly so. The liver 

 showed slight cloudy swelling, and the intestines were distended with 

 gas. The right heart was in diastole and was filled with fluid blood, 

 while the left heart was in systole. Heart blood cultures were made 

 from each and later plated. 



Experiment III. One hundred c.c. of the experimental sewage was 

 diluted with 2,000 c.c. of tap-water containing about 4,800 organisms 

 per cubic centimeter. This was thoroughly shaken and after removing 



