“The soil is, as a matter of fact, full of live organisms. It is essential to conceive of it as something pulsating with life, not as a dead or inert mass. There could be no greater misconception than to regard the earth as dead: a handful of soil is teeming with life. The living fungi, bacteria, and protozoa, invisibly present in the soil complex, are known as the soil population. This population of millions and millions of minute existences, quite invisible to our eyes of course, pursue their own lives. They come into being, grow, work, and die: they sometimes fight each other, win victories, or perish; for they are divided into groups and families fitted to exist under all sorts of conditions. The state of a soil will change with the victories won or the losses sustained; and in one or other soil, or at one or other moment, different groups will predominate.”