This is the most common method for counting pollen grains. A drop of a known volume of suspension of collected pollen is placed under the microscope and the number of pollen grains counted allowing the calculation of the total number of pollen grains in the whole volume. Haemocytometers were initially developed to count blood cells, but they can also be used to count the number of pollen grains in a standard volume of liquid containing pollen (see Human et al., 2013 for more information on using haemocytometers in honey bee research). The steps are as follows:
- Collect pollen as described in section 3.1.
- Suspend pollen grains in a known volume of 70% ethanol and vortex to assure homogenous mixing.
- Remove a sample of pollen suspension with a pipette and place in haemocytometer.
- View and count pollen grains under a microscope. Haemocytometer manufacturers provide the known volume of suspension under the viewing area and provide easy instructions for extrapolating object counts back to absolute counts in the original suspension (sample).
- When the number of pollen grains is very low, a measured drop of the suspension can be placed on a lined microscope slide and all the grains counted.