NOOES ON BACTERIOLOGY.
ACTERIOLOGY is daily attracting more and more attention as a study, and to those connected with water works, it is one of the highest importance — more important, perhaps, than ever, since a Wisconsin court has granted a widow $5,000 damages against a water company because her husband’s death was said to be traceable to polluted water which occasioned typhoid fever. As this case has been appealed to the Supreme court, it may turnout upon further investigation that the water company was not to blame, and that it had taken all proper precautions not only tc supply wholesome water, but also to have that water constantly rested by competent experts.
It must be remembered that, while a bacteriological examination may consist of counting the number of bacteria per cubic centimetre and searching for the typhoid bacillus coli communis, the former is rarely found in drinking water, although most positively known to be present ; while the latter—as a constant quantity in fasces—indicates, and is the main evidence of sewage pollution. Such water, therefore, can be labeled as dangerous, but not as certainly typhoid-producing. Thus a bacteriologist, who looks simply for something in suspense, may pronounce water harmless, which the chemist,who looks for something in solution, may condemn as poisonous. The bacillus may be temporarily tiltered—especially in the case of well water, while the soluble matters are not affected ; on the other hand, the polluting matter may be so largely diluted as to defy its revelation by chemical tests, though the coli bacillus may be sufficiently present to give a positive indication. Thus, the water supplied to Newark, N. J., is from a chemist’s standpoint of excellent quality, yet, owing to the conditions of the watershed.many coli bacilli must get into the water every day. In the same way some water from a well close to a cesspool was examined chemically and pronounced grossly impure, while a bacteriological examination had failed to discover any coli bacilli,which had simply been filtered out by the soil. In such cases neither bacteriologist nor analytical chemist can be blamed, and under different conditions—for example, it the coli bacilli made their way through the soil, or if the specimen of water sent to be analysed had been drawn when the water was less diluted, the verdict might have been entirely reversed. Wherefore, the conclusion to be arrived at is, that, if water works companies—or the commissioners of municipal water supplies wish to be altogether on the safe side, prudence would dictate the testing of the water both chemically and bacteriologically.
The chief difficulty as to he detection of the typhoid bacilli is the lack of definite characteristics in those bacilli themselves. But then, variability is one of the most striking features of all bacteria. They vary in shape; they are ‘subject to variability in all their vital manifestations — production of pigment and disease, fermentation, and the like — and to variability in the capacity of living in various media. In the case of certain bacteria it is possible to force them to produce certain products of growth by gradually introducing certain substances into the nutrient medium, to the presence of which the bacteria may become accustomed, though its sudden exhibition would be sure to inhibit their growth or even to destroy them. To go farther: Bacteria may even be finally stimulated to increased growth by the gradual introduction of of germicides. External conditions and environment are powerful factors in causing this variability—indeed, the sensibility of bacteri to such conditions has been thoroughly tested and is now fully recognized. A recent writer, B. Meade Bolton, insists that bacteria possess no characteristic that is not subject to variation. He says:
The anthrax bacillus, ordinarily a sharp, shortly cut rod, forming spores or resistent bodies under favorable conditions and capable of producing a virulent, infectious disease in man and animals, sometimes becomes so distorted in shape as to be unrecognizable under the microscope It may be made to lose its power of forming spores and of producing disease. The diptheria bacillus is sometimes a fine, uniformly stained rod; at others it appears as a large, irregularly nodular rod. Sometimes both ends are swollen and apparently distorted; sometimes one end alone. Sometimes the rod stains irregularly; the protoplasm is collected into clumps and granules in the cell membrane. T e bacillus prodigiosus frequently resembles a coccus, and at other times appears as a distinct rod, or even a short thread. This organism, which ordinarily forms a deeply red mass on the nutrient medium, frequently loses its power of producing pigment.
In the general consideration of bacilli, therefore, this property of variability must not be lost sight of; nor must the fact be forgotten that bacteria are not chemical compounds,but living cells, each possessing singly moreor less individuality; while all agglomerations of cells have variable characteristics as may be seen by experimenting upon them with disinfectants, the use of a certain amount of which may destroy many of the organisms, and yet leave many more unaffected; may kill more of the organisms in one culture than in another.
This variability extends likewise to the vitality of the bacteria in water. The typhoid bacillus, when introduced purposely into water, has lived for thirty days; yet it has frequently been found to die out in a much shorter space of time. Pathogenic bacteria will sometimes diminish and disappear much more quickly than at other times. This, of course, is determined by the number of bacteria introduced into the water, and certain factors in the water itself—such as its temperature, its special adaptability to the bacilli so introduced, the number of other kinds of bacteria already in the water,the amount of nutrient organic matter, and the like. Expedience has shown that pathogenic bacteria, when introduced into water, do not multiply, but disappear. This took place in very foul water from a shallow well, even after it had been sterilized. Only after the addition of peptonized beef broth to the water did a multiplication of the bacteria take place. It was necessary to add an amount of such beef broth, estimated to contain sixty-seven millegrams of organic matter to a litre of water, before any growth of the typhoid fever bacillus could be obtained, and the equivalent of 400 millegrams of organic matter in the case of the cholera organism. Not only is such an amount of organic matter never found in the most contaminated water, but the kind of organic matter ordinarily used in the experiments is never found in the contaminated water. It may also be added that the kind of organic matter ordinarily found would be much less suited for the typhoid and cholera bacillus than the above mentioned carefully prepared peptonized broth used in the experiments. It may, therefore, safely be stated that, where water is contaminated with pathogenic bacteria, these will rapidly disappear, owing to lack of proper nutrition as well as to the conflict and competition for existence with the saprophytes, the other bacteria always found in contaminated water.
(To be continued.)