What we see here is usually called a "hay infusion". What is a hay infusion? Well, many young (and older) microscopists have heard about the "world in a drop of water" only to be very disappointed by finding very little if anything in pond water. Though pond water contains microbes that can be seen even by using cheap toy microscopes, they typically aren't very dense, making them very hard to find.

The solution to this dillema is known as a "hay infusion", pond water is poured into a container stuffed with dried grass (such as lawnmower clippings). The theory is that the dried grass is food for the bacteria already present and these are eaten by the microbes, resulting in a population explosion! Always being eager to experiment, and not having any pondwater available, I decided to take fresh plucked green grass, stuff it in a vial, and add "aged" tap water (chlorine removed). The result can be seen here. After just 48 hours there were already microbes in abundance! Dried grass would work better and pond water would give a better variety of microbes but this experiment shows that even green grass and plain water will work.

Since there was no "starter culture" of pond water, you might wonder where the microbes came from. The answer is that they were already there on the grass as spores. The fact that they showed up so quickly suggests that they "come out and play" every time the grass gets a good soaking , as in a rainstorm, leaving spores behind to await the next soaking. These creatures also inhabit damp soil, some of which got mixed in with the grass.