Diatoms are brown microalgae that can be found in all freshwater and marine environments. They are an important link in the ecological cycle. In streams and rivers you often see stones covered with a brown layer that is formed by diatoms.

A few years ago I saw that the ditch behind our garden house at garden park Nieuw Vredelust was completely covered with some kind of duckweed. On closer inspection it turned out to be a water fern, so not a duckweed at all. It was the first time that I saw this in a ditch.

The reason for writing something about aphids was a Willow Tree in our garden that was infested with these very small insects. Aphids mainly reside on young leaves and stems. With the naked eye there is not much more to see than small, slowly moving oval shapes that are a few mm in size. All the more reason to have a look at them under magnification.

The inside of the oral cavity is covered with a layer of squamous epithelial cells. These are relatively large, flat cells that are constantly being produced and rejected by the oral mucosa. It is quite easy to examine these cells microscopically.