When I had got the focus adjusted to suit my eyes, I must confess that I was astonished by what I saw. Somehow, in the course of my reading, I had picked up the idea that bacteria were rod-like creatures which floated inertly in liquids at the mercy of the currents; but at the first glance I realised how much below the reality my conception had been. In the field of the instrument I saw a score of objects, rod-like in their main structure, it is true, but so mantled with the fringes of their fine, thread-like cilia that their baculite character was almost concealed. Nor were they the inert things which I had supposed them to be; for, as I watched them, now one and again another would dart with prodigious swiftness from point to point in the circle of illumination. I had rarely seen such relative activity in any creature. The speed of their movements was so great that my eye could not follow them in their tracks. They appeared to be at rest one instant and then to vanish, reappearing as suddenly in some fresh spot. I watched them, fascinated, for some minutes, trying to trace the vibrations of the cilia which projected them from place to place at such enormous speeds; but either my eye was untrained or the movements of the thread-like fringes were too rapid to be seen. It was certainly an illuminating glimpse into the life of the under-world. When I had risen from the microscope table, Wotherspoon took me over to one of the benches before the window and showed me the glass vessels containing the pinkish gelatine. These slabs, he told me, were cultures of bacteria. One placed a few organisms on the gelatine and there they grew and multiplied enormously. “These specimens here,” said Wotherspoon, “are not the same variety as the ones on the microscope slide. They have nothing whatever to do with disease; and yet, as I told you, they have an influence upon animal life. I suppose you never heard of nitrifying and denitrifying bacteria?” I admitted that the names were unfamiliar to me. “Just so. Few people seem to take any interest in these vital problems. Now you do know that internally we swarm with all sorts of germs, noxious in some cases, beneficent in others; but I suppose it never struck you that our bodies form only a trifling part of the material world; and that outside these living islets there is space for all sorts of microscopic flora and fauna to grow and multiply? And need these creatures be absolutely isolated from the interests of animals? Not at all. “Now what is the essential thing, apart from air and water, which we derive from the outside world? Food, isn’t it? Did it ever occur to you to inquire where your food comes from, ultimately?” “Well, of course,” I said, “it comes from all over the world. I don’t know whether the wheat I eat in my bread comes from Canada or the States or Argentina, or was home-grown. It doesn’t seem to me a matter of importance, anyway.”