NOTES ON BACTERIOLOGY.
IN continuing the subject of the vitality of the pathogenic germs under certain conditions of soil, water, etc., Dr. Miquel’s “Anti-infection of Waters” may be quoted. In that work he says that, when samples of various water, pure and impure, are maintained at a constant temperature of sixty-eight degrees Fahr., they vary differently in the matter of the increase of their bacterial contents. With pure water the increase is rapid and temporary, while with impure water it is slow and lasting. In a recent number of the *’ Annales de Micrographie ” Dr. Miquel gives the results of some interesting, not to say startling observations he made in respect of the vitality of disease germs. In May, 1881, he took some earth from the Montsouris park at a depth of ten inches below the turf. This he dried for two days at a temperature of thirty degrees Cent., ar.d then he placed the dust in hermetically sealed tubes, which he put aside in a dark corner of the laboratory. When taken, the soil contained an average of $6,500,ooo’bacteria per gramme. After desiccation the number had fallen to rather less than 4.000,000 Sixteen years later, that is to say, last year, he still found 3,500,000 per gramme, and he was enabled to isolatt the specific microbe of tetanus. The inoculation of this soil in guinea pigs determined death from tetanus after an incubation period of two days, showing the remarkable vitality of pathogenic microbes under favorable conditions.
Dr. Bolton, another eminent bacteriologist, states that bacteria rapidly decrease in number when intentionally introduced into water. This is probably due to the presence of toxines produced either by these or other bacteria. These toxines are very volatile, and the following interesting experiments described by Professor Mason furnish in a striking manner the deadly effect of the toxines on bacteria. Some water slowly distilled in a special apparatus at a temperature between 86 degrees and 95 degrees Fahr., was noculated with the germs from 1,650 litres of air. The number of bacteria found in the water was immediately 75 P cent.; six days, 7 P cent.; sixteen days, 1.5 percent.; twenty-seven days. 1.5 per cent. Professor Mason’s next experiment showed a difference. River water sterilized in the ordinary manner was inoculated with germs from twenty litres of air. he number of bacteria per cubic centimetre immediately, 6.5 per cent.; seven days, 75°** 000 per cent.; ten days, 900,000 per cent.; thirty-one days, 16,750,000 per cent.; ninety days, 62,500 per cent.; 273 days, 48,000 per cent.
According to an eminent English authority, bacteria can be classified almost without question—and contrary to the claims put forth by zoologists—among the simplest of the plant forms and as near relatives to the alga;. The most common form is rod shaped, thou ;h others are spiral, spherical,and egg-shaped. In size they vary considerably. Some are of the larger forms, 20-25,000 of an inch long, while one of the smallest is 1-50,7 000 of an inch. The minuteness of one class is so marked that 1,500 cf them placed end to end will hardly reach across a pinhead—extremely powerful lenses being necessary to observe them and their workings. Even then, as the little bodies are almost transparent, the microscopist is obliged to stain them with some dye to render them something more than shadowy and indistinct. Some, however, massed together in large quantities, make a brilliant showing, and the phosphorescent lights seen in many bodies of water and on decaying wood or vegetables are believed to be produced by immense numbers of massed bacteria. Other kinds have a blue or a greenish tinge, and one of the most striking of all is scarlet in color, as observed in the little cells collected in such large quantities on certain moist organic substances.