84 ELEMENTS OF WATER BACTERIOLOGY. 



in the examination of small portions of the water." It 

 should be noted that Hammerl's method was much less 

 delicate than the use of the dextrose tube for preliminary 

 incubation. 



A very important series of observations carried out in 

 England by the bacteriologists of the local government 

 board has led to similar conclusions. Dr. Houston in 

 particular (Houston, 1898; Houston, i899 a ; Houston, 

 1900*) made an elaborate series of examinations of soils 

 from various sources to see whether the microbes con- 

 sidered to be characteristic of sewage could gain access 

 to water from surface washings free from human con- 

 tamination. In the three papers published on this sub- 

 ject the examination of 46 soils was recorded. In only 

 10 of the samples was B. coli found, and of these 10, 9 

 were obviously polluted, being derived from sewage fields, 

 freshly manured land, or the mud-banks of sewage-pol- 

 luted rivers. The author finally concluded that "as a 

 matter of actual observation, the relative abundance of 

 B. coli in pure and impure substances is so amazingly 

 different as to lead us to suspect that not only does B. coli 

 not nourish in nature under ordinary conditions, but that 

 it tends to even lose its vitality and die." " In brief, I am 

 strongly of opinion that the presence of B. coli in any num- 

 ber, whether in soil or in water, implies recent pollution of 

 animal sort." Pakes (Pakes, 1900) stated on the strength 

 of an examination of "about 300 different samples of 

 water," no particulars being published, that water from 

 a deep well should not contain B. coli at all, but that water 



