08 
which filled up the lakes, during the rains of October, Nov- 
ember, December and the first week of January, has had 
ample time to get thoroughly well sunned, settled and stored. 
The consequence is, that, in no less than 4 instances out of 
12, fecal bacilli could only be found in more than 50 c.c. In 
no case were samples obtained which contained more than 
one fecal organism per c.c. In comparing this quarter with 
the last the percentage prevalence of organisms presents 
little change. The organisms of medium powers of resist- 
ance still preponderate very largely. Lactis ezrogenes and 
coscoroba are fairly plentiful. Cloace has fallen off to an 
extraordinary extent; this is undoubtedly due to the ten- 
dency for these organisms to remain at the bottom of lakes, 
as has been demonstrated in Chapter VIII. Bacillus Grunthal 
is not common. It is obviously outnumbered by such or- 
ganisms as lactis erogenes and coscoroba. No coli communis 
were found in the analyses of this quarter. 
The study of the results of the analyses obtained, side 
by side with the prevailing meteorological condition, demon- 
strates the extraordinary efficiency of these natural forces in 
getting rid of all but the most resistant elements of a pollution 
which is very great in amount at certain times of the year. 
These remarks and tables of figures were compiled as 
long ago as the summer of 1908, and since that time we have 
had opportunities for correlating results that have been ob- 
tained in Madras and Bengal during more than two years. 
Table No. IX (c) gives the results of the prevalence of organ- 
TABLE IX (c). 
Percentage Prevalence of Organisms, Madras Lakes and Storage 
Tank, year Igto. 

Quarter Quarter Quarter | Quarter 
ending ending ending ending 
March 31.'| June’3o0. | Sept. 30. | Deere 

Bacillus Grunthal-Vesiculo- | 
sus - — 21°4 6°6 31°2 30 
Coh communis 
Schafferi : Ni ao 2°4 Nil. 
Lactis erogenes .. 24°9 20°0 6'2 43°1 
Cloace ne 36°2 5 6°2 res 
7 
9 

