458 



SCIENCE. 



[N. S. Vol. XI. No. 273. 



typhoid fever in the city of 55,000 inhabi- 

 tants using this filtered water. 



This city filter was built in 1893, and, 

 while the death rate from typhoid fever in 

 Lawrence for a number of years before its 

 construction averaged about 12 per 10,000 

 inhabitants ; the first year after construction 

 the rate was 4.75 per 10,000 inhabitants, 

 and this was followed by a steady yearly de- 

 crease to 1.39 in 1898. During this period 

 there was no unusual disturbance of the 

 sand filter bed, and its bacterial efficiency 

 was good. 



In the fall of 1898 it was necessary to 

 relay some of the underdrains of the filter, 

 and some of the sand beds were very much 

 disturbed. When the sand was replaced 

 and water was again passed through the 

 filter the entire effluent was pumped to the 

 reservoir and used in the city. Following 

 the conclusion of this work, B. coli com- 

 munis was found in 1 c.c. of 72 per cent, of 

 the samples of the effluent of the filter ex- 

 amined during December ; 54 per cent, of 

 those examined during January ; 62 per 

 cent, of those examined during February ; 

 and 8 per cent, of those examined daring 

 March. The bacterial efficiencj' of the 

 filter, or percentage removal of total num- 

 bers of bacteria in the applied water, was 

 92.20 per cent, from December 10th to 

 31st ; 98.31 per cent, in January ; 98.17 per 

 cent, in February; and 99.89 per cent, in 

 March. 



During the period from the end of the 

 disturbance of the filter in December until 

 the end of the month there were twelve 

 cases of typhoid fever reported in the city ; 

 during January, 59 cases ; during February, 

 12 cases ; but in March, when B. coli com- 

 munis had practically disappeared from the 

 effluent of the filter, there were but 9 cases, 

 and these during the first portion of the 

 month ; that is, during the months of De- 

 cember, January and February there was 

 an epidemic of typhoid fever in Lawrence. 



During this period, B. coli was present in 

 1 c.c. of samples of effluent of the filter ex- 

 amined to the extent denoted by the figures 

 given. When it failed to be found in 1 c.c. 

 the epidemic had ceased. When 100 c.c. 

 of the effluent were examined, B. coli was 

 found more frequently, but the figures and 

 facts in regard m the epidemic seem to show 

 that, when filtering a river water as polluted 

 as that of the Merrimac, it is safe to assume 

 that, when coli is found only infrequently in 

 1 c.c. of the effluent, the typhoid germs, 

 necessarily fewer in number, and more easily 

 removed by the filter, have been eliminated 

 from the water. The death rate of the city 

 from typhoid fever in 1899 was 3.00 per 

 10,000 inhabitants. 



On the detection of bacillus Coli communis in 

 ivater : Peofessoe E. O. Joedan. 

 The direct application of the fermenta- 

 tion tube method to greatly polluted waters 

 sometimes meets with a serious difficulty. 

 This is the fact that other gas-forming spe- 

 cies (and perhaps some non-producers of 

 gas) overgrow B. coli and obscure or falsify 

 the typical reaction. This appears to hap- 

 pen at least with some river waters more 

 commonly than has generally been sup- 

 posed, even when extreme dilutions are em- 

 ployed. One species that interferes often 

 with the growth of B. coli is a variety of B. 

 cloacce, and when mixtures of pure cultures 

 of this microbe and of B. coli are introduced 

 together into fermentation tubes, the former 

 frequently gains the upper hand. 



A method that has given promise of over- 

 coming this difficulty, and some others, is 

 the following. The desired quantity of 

 water is incubated in acid carbol broth, 

 1. c.c. of the required dilution being added 

 to 5 c.c. of broth made 5 to 5.5 acid on 

 Fuller's scale, and containing carbolic acid 

 in the proportion of 1-1000. After inocula- 

 tion at 38°-40° for 12 to 18 hours, platings 

 are made in litmus lactose agar, and colo- 



