Sessional_Paper_1911 — Page 192

THE POKFULUM UNFILTERED WATER.

The following Tables give the condensed results of the examination of 130 samples of the total mixed unfiltered water as it flows on the filter beds.

The following amounts of each sample were examined :-

The first

38 samples

cc, cc, lec on agar plates.

cc, lec, 2cc on Lactose Agar coloured plates.

lec, 2cc, 5cc on to Lactose N. R. Bile Salt Peptone water.

Icc, 2cc, 5cc, 10cc, 20cc on the Glucose N. R. Bile Salt Peptone water.

The examination of the next 40 samples was the same with the exception that the 10cc and 20cc amounts of the samples were added to Lactose Peptone water instead of to Glucose Peptone water.

From the 79th sample onwards, the Lactose Agar coloured plates were given up and ce of the sample added to the Lactose and Glucose Peptone waters instead and in addition to the other amounts.

The plating out and isolation of colonies was done as already described.

The Coli Group" results are recorded in two columus, 1st the Group results, 2nd the organisms considered to be more or less identified.

For the Group results, an organism which gives acid and gas in Lactose and Glucose; acid and clot in Litmus milk; is Motile and non Gram staining; gives Indol in Peptone water and fluoresence in Neutral Red and does not give a Vosges and Proskauer reaction and does not liquefy gelatine in 10 to 14 days, is regarded as positive and recorded by the sign+. If any of these reactions are negative, the fact is recorded in brackets, e.g.,

+ (Indól − ).

-

These organisms were also tested for acid and gas on Saccharose and Dulcit and the result recorded thus + (S-S+) or + (S+D+) etc. In this way the organisms can be clas- sified into the four groups of MacConkey,

The organisms isolated from the first 94 samples were however in addition fully worked out by the set of tests given on page 119 and where the organisms gave the necessary reactions, MacConkey's identification numbers are given. Only the chief organisms are recorded here; organisms of doubtful characters are not noted but will be dealt with when the whole of the organisms worked out are discussed.