99 
isms during the four quarters of the year 1910 in lake waters 
in the Madras Presidency. During the year 1gro the rainfall 
was very equally divided over the whole of the year. In 
each quarter a certain amount of rain fell in most places; 
the consequence is, that although the table does not exactly 
tally with Table IX (6) which was made from figures obtained 
in 1908-09, it still shows in a marked degree the prevalence of 
certain bacilli at various times of the year, viz.: (1) the dry 
quarter of the year (with the exception of Kunoor and Oota- 
camund supplies) was from December to March, and in this 
quarter a very decided prevalence of cloace is observed. 
The Ootacamund and the Kunoor reservoirs, which have 
received rain, account for the prevalence of lactis erogenes 
during this quarter. (2) By far the wettest portion of the 
year was the 2 quarters ending September and December, 
in every place heavy rain fell. In the first of these quarters 
(ending September), the waters were highly polluted and 
show mixtures of bacilli. There is no great prevalence of 
lactis erogenes, nor of cloace. In thesecond of these quarters, 
although a great deal of rain fell, a certain amount of puri- 
fication has gone on, and bacillus lactis erogenes is the most 
common organism isolated. Bacillus cloace is, as compared 
with hot weather samples, a rare organism. 
For the same year the samples obtained from rivers have 
been tabulated. Of course, it must be understood that rivers 
never show the stages of purification as clearly as lakes, 
because pollution may be added at all times along the banks. 
Table IX (d) gives the results for the Madras rivers. Again, 
TABLE IX (d). 
Percentage Prevalence of Organisms in Madras Rivers, year 


IgIo. 
Jan.-June. July-Dec. 
Bacillus Grunthal-Vesiculosus. be 29°3 22°9 
m Colicommunis and Schifferi 5 8°Z 
a Lactis ezrogenes ae ion 15‘0 25°8 
Cloace ae aoe, ine 1365 I°7 


