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Haying ascertained this, I determined to discover the ratio of thickness between the body of the Bacterium and its flagellum that is to say, to discover how many of the flagella laid side by side would make up the width of the body. I proceeded thus: This is a complicated microscope placed on a tripod, so arranged that it may be conveniently worked upright.
Glanders is due to the action of a specific bacterium, the bacillus mallei, which resembles the tubercle bacillus, save that it is somewhat shorter and broader, and does not stain by Gram's method.
Moreover, from Africa there is always something new in the way of tropical diseases, and presently Africa, if we let it continue to fester as it festers now, may produce an epidemic that will stand exportation to a temperate climate. A bacterium that may kill you or me in some novel and disgusting way may even now be developing in some Congo muck-heap.
In its further growth the gelatine is liquefied in the vicinity of the colony, which at the same time sinks down deeper into the gelatine mass, and makes a small thread-like excavation in the gelatine, in the center of which the colony appears as a small white point. This again is peculiar; it is never seen, at least so marked, with any other bacterium.
Thus a "primitive feeder," the bacterium Nitrosomonas, "for combustion ... takes in oxygen directly through the intermediate action of iron, phosphorus or manganese, each of the single cells being a powerful little chemical laboratory which contains oxidising catalysers, the activity of which is accelerated by the presence of iron and manganese.
The phenomena are as massive and wide-spread as is anything in Nature, and the study of them is as tedious, repellent and undignified. To reject it for its unromantic character is like rejecting bacteriology because penicillium glaucum grows on horse-dung and bacterium termo lives in putrefaction. Scientific men have long ago ceased to think of the dignity of the materials they work in.
It is true that there is a considerable range in size between the microscopic bacterium at one extreme and the elephant or whale at the other, but this is far less extensive than in the case of lifeless things like water and stone. In physical respects, water may be a fluid, or a gas in the form of steam, or a solid, as a crystal of snow or a block of ice.
This mass proves to be made of bacteria which have the power of absorbing oxygen from the air, or, at all events, of causing the alcohol to unite with oxygen. It was at first thought that a single species of bacterium was thus the cause of the oxidation of alcohol, and this was named Mycoderma aceti. Each appears to act best under different conditions.
Still another list might be given of diseases whose general nature indicates that they are caused by bacteria, but in connection with which no distinct bacterium has yet been found. As might be expected also, a larger list of animal diseases has been demonstrated to be caused by these organisms.
This view of the case brought Pasteur to a large and general investigation of bacteria. The bacterium may be defined as a microscopic vegetable organism; or it may be called an animal organism; for in the deep-down life of germs there is not much difference between vegetable and animal perhaps no difference at all.
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