1911, demonstrate these points to a remarkable degree. 
43 
Note 
that in Table Nc. VI(c) the mid-summer figure in raw and 
filtered water always shows a less percentage of 
* tre 
coli’’ (lactose + glucose + indol + ) than the figures of the winter 
months. 
Further, Table VI(d) for the 3 years taken from Hous- 
ton’s report also demonstrates the fact that water after storage 
contains a very much higher percentage of ‘‘ non-typical coli, ’’ 
that is (lactose — glucose + ) than do unstored or raw waters. 
TABLE VI(d). 
TYPE OF B. COLI. 
After Houston. 

19CQ. 
Type of B, coli. 
Raw Waters. 
Out of 2,595 speci- 
mens of B. coli iso- 
lated from 696 samples 
cf raw water, the pro- 
portion between the 
typical and non-typical 
races of B. coli, ex- 

was as follows :— 

pressed as percentages, 
Filtered Waters.* 
Out of 3,164 specimens 
of B. coli isolated from 
7,081 samples of #ltered 
water (including Kent 
and Lee Valley un- 
filtered well water), the 
| proportion between tbe 
typical and non-typical 
races of B. coli, ex- 
pressed as percenta ges, 
was as follows :— 

Typical B. coli (+lactose ;+indol) 
{i +lactose ;—indol) 
Non-typical B. coli 
| (—lactose ; + glucose) 
79°4 
11‘9 | 
- 20° 
yeh 


1G10. 
Type of B. coli. 
Raw Waters, 
Out of 2.427 specimens 
of B. coli isolated from 
#612 samples of raw 
water, the proportion 
between the typical 
and non-typical races 
lof B. coli, expressed 
as percentages, was as 
follows :— 

Typical B. coli (+Jactose ; +indol) 
( (+ lactose ;+indol) ... 
Non-typical B. coli- 
\( —lactose ; + glucose) 
80°o 
| 
| 
8°7 | 
Se dee 
Filtered Waters.* 
Out of 3,934 Specimens 
of B. coli isolated from 
| 6,219 samples of filtered 
| water (including Kent 
land Lee Valley un- 
filtered well water), the 
proportion between the 
typical and non-typical 
races of B. coli, ex- 
pressed as percentages, 
was as follows :— 



* Filtered waters all have more or less storage and exposure to sun. 
