Sessional_Paper_1907 — Page 876

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The organism may gain access to a water from sources other than sewage, but its presence in appreciable numbers in any water coupled with the general bacteriological characters of the water, is commonly considered as evidence of contamination. Most authorities agree that the higher the number of B. coli, the heavier will have been the recent sewage pollution, and the greater the probability of the presence of disease producing bacteria. Conversely, if B. coli is not present, one may presume that such disease producing bacteria as B. typhosus will also be absent, and the sample of water might be used for drinking purposes.

Water efficiently filtered ought not to contain B. coli, and when filtering polluted water, the presence of B. coli is a very delicate test of filter efficiency. Drinking water from a deep well should contain no B. coli

In condemning or approving of a water for drinking purposes, all the findings of topo- graphy, bacteriology, and chemistry, must be considered, and too much relance must not be placed upon any single phenomenon or reaction.

The Preparation of Vaccine, Lymph.

On the opening of the Bacteriological Institute, the Vaccine Institute, situated in Kennedy Road, was vacated and handed over to the Government.

During the year 1906, the preparation and distribution of Small Pox vaccine was efficiently maintained. Apart from the regular supply of vaccine lymph to Government Medical Officers, Chinese Hospitals, and Public. Vaccinators, a large number of tubes has been sold to the outside public. The number of tubes issue was 8.797. the value of which was $3,020.50. 4,257 tubes were paid for, the sum of $1,430,50 being paid into the

reasury.

1

The attched Tables Nos. V and VI show the extent of the work done during the past year. The method, which is still adopted for the manufacture of the lymph, is the intimate mixture of the fresh lymph and pulp with glycerine and distilled water. The chloroform method of Green, has not given good results.

Table No. I.-Epimuic Plague.

(a.) Total No. of Victoria Rats examined,

1902,

1903,

1904,

1905, 1906,

1

.22,710

Kowloon

7,991

Total No. of Hongkong Rats examined,

...30,701

(b.) Total No. of Victoria Rats found infected,

1)

Kowloon

"}

Total No. of Hongkong Rats found infected, ........

511

168

679

Table No. II.-Incidence of Epimuic Plague during the last five years.

Year.

No. of Rats examined.

No. of Kats found infected.

Percentage found infected.

117,839

2,015

1.7%

101,056

3,744

3.7%

21,907

993

4.5%

30,888

1,450

4.7%

30.701

679

2.2%