In it, an apparently normal-looking petri dish is treated so as to reveal a message when wetted with water vapor. The contrast between hydrophobic and hydrophilic surfaces, which is not visible to ...

The petri dish is placed on a clear plastic platform and a mirror underneath tilts and rotates, giving a full view of the dish while magnifying up to 3X. The Cell-Colony Reader can also be used to ...

Petri dish A glass or plastic circular dish. Used in combination with agar to grow cells. Quadrat A square grid, often 1m squared. Used to sample plants or slow moving animals e.g. snails.