DR CHAMPTLOUP'S LECTURE.

King Country Chronicle, Volume VII, Issue 572, 31 May 1913, Page 7

DR CHAMPTLOUP'S LECTURE.

(Concluded.)

The method of counting the bacteria may interest you. An accurate quan tity—generally a cubic centimetre — of the milk is mixed with varying quantities of sterile water, so that highly diluted in definite proportions. A cubic centimetre of each of these dilutions is now added to liquefied culture medium, thoroughly mixed, and the whole poured into one of the glasß capsules called petri dishea. Wtha the medium has set. the series as put in the incubator for 48 hours, and then examined with a hand magnifying gass. Each bacterium present in the original dilution of the milk will now have inultipied to such an extent, as to have formed a visible growth. The number of these visible growths, or colonies, as they are called, is then counted, and by a process of multiplication we find the number of bacteria per cubic centimetre in the milk sample. A cubic cetimetre represents about a third of an ordinary thimbleful. In this way the number of bacteria in the city water supply was counted, and the average of a series gave 350 bacteria per cubic centremetre, though thiß varies considerably at different periods of the year. Then some of the same water was filtered through an ordinary charcoal filter, and a comparison of the two lantern slides shows that there is a considerable reduction in the number of bac teria present. SAMPLES OF MILK. Next, the following series of milk samples was examined: No. 1 sample of milk may be taken as the ordinary milk supply as delivered. The number of living baceria per cubic centimetre was 32,000. Next, a sample of humanised and pasteurised milk, freshly prepared, which gave only 2700 living bacteria per cubic centimetre. Note the very great improvement as a result of pasteurisaion. Next, samples A, B, (J, and D, from cows milked under varying conditions, and the examinations made almost immediately. Sample A was milked with every possible precau 7 tion, and ths low count of 50 organisms per cubic centimetre was recorded. Sample B was milked under similar, though less rigid, precautions, and the count was 4400 per cubic centimetre. Sample C was milked with ordinary care, su n h as the washing of the cow's udder, milkman's hands, and the rinsing out of the bucket with hot water. Such conditions should be, at least, an absolute requirement of all dairymen. The count in this caße mounted up to 10,800 per cubic centimetre. Sample D was milked, as 1 am afraid too many cows are milked, with no special care with regard to cleanliness, with a resulting count of 57,000 per cubic centimere. The difference between the four samples is remarkable,, and speaks volumes in favour of clean milking, and yet, as milk goes, none of them is a very bad sample. Twenty-seven samples of milk is supplied from door to door were then examined, and the average count found to be 10,700 organisms per cubic centimetre. Similar experiments in a large American city gave an average of 11,270,000 per cubic centimetre, so that our milk, at the time of examination, compares more than favourably with that city's supply. Rosenau, in a recent book on milk supplies, states that certified milk should never exceed 10,000 bacteria per cubic centimetre, and that health officials should endeavour to keep the general supply below 100,000 bacteria per cubic centimetre. In conclusion ladies and gentlemen I have endeavoured to tell and show you something of those wonderful little plants we call bacteria, and the experiments we have ''made with milk prove that with ordinary cleanliness and care we can secure our food sup plies, more particularly milk, meat, and fish, in a state of comparative purity. What I want you to consider is this: Is it not worth while paying a little more for milk which our dairyman can certify as produced under the moat cleanly conditions, and from cows certified as free from disease? Or, is it not worth patronising the tradesman who screens his shop from flies and dust, and serves our meat, fish, or fruit in a cleanly manner? At the recent Tuberculosis Conference in Wellington we pasßed a resolution recommending as an initial step that hospital boards should lead the way by requiring that their milk supplis should be certified—a recommendation which am glad to say, the Otago Hospital Board have wisely adopted.