Lab 1. Structure, movement and response of Paramecium
This lab is done under the teacher’s supervision. A drop of hay infusion prepared 2–3 weeks earlier is placed on a slide with a pipette, cotton fibres slow the Paramecium down, and a cover glass is put on top. The slide is viewed first with the low and then the high objective; you find the front and rear ends, the oral groove, the cilia and the two contractile vacuoles. To see response, a drop of clean water and a drop of infusion are joined by a thin channel and a few tiny salt grains are added to the infusion: the Paramecia swim from the salty side toward clean water. The stinging trichocysts and nuclei are shown only by the teacher with a chemical solution (acetic acid and methyl green); pupils do not handle these substances. When using the microscope do not let the objective touch or crush the slide. Record what you saw in your notebook with a drawing.
Work in pairs: one looks through the microscope, the other writes, then swap. Safety: only the teacher works with acetic acid, dyes and glass pieces; do not break the glass; wash your hands with soap after the work.