1. 35- or 60 mm Petri dishes coated with a thin layer of 1% agarose in water, previously sterilized by autoclaving.
2. Two pairs of no. 5 Dumont watchmaker's forceps, sharpened using an "Arkansas" sharpening stone.
3. Tungsten needles are made by mounting about 5 cm of tungsten wire (0.5-mm diameter. 99.95% purity, Goodfellow metals) in a 7 cm piece of capillary tubing. The needle is sharpened by electrolysis in 1 M NaOH using a potential difference of 9-12 V AC. The simplest procedure is to place a small piece of modeling clay on the end of the wire and to dip about 2 mm of naked wire into the NaOH. When the clay falls off, the needle is sharp enough.
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