When you are trying to do research at a community college, the little things can be challenging. Like counting cells. Pretty soon its going to be really important that I be able to count algal cells pretty danged accurately in order to have my students hunt for algal viruses in local streams and ponds. This can be done indirectly by using a spectrophotometer to measure the amount of light that a tube of cells absorbs/refracts (especially if they are green, like algae), and multiplying the amount of light absorption by a known constant that gets you back to cell number (cell number and amount of light absorbance should be directly correlated) – but that isn’t a direct count. Back in the day I counted cells many times every day. Its really important when you are doing virus infections to know exactly how many you have in your plate. But in research labs you do this with a counting slide or hemocytometer, which cost over $400 for one slide, so it seems unlikely that we would have that here.
Until your colleague shows you a box of miscellaneous microscope stuff in it hidden in a drawer:
This might not be obvious, but this is a gold strike for me. Don’t worry, this project has nothing to do with sperm. Or bacteria.
It might not look impressive, but those lines tell you the exact volume of liquid you are looking at, so once you count your cells, you divide it by that volume (you are looking at approximately 0.00008 ml) and bazinga, you are done. The little green dots are Chlorella, the green algae.
Just in case I forget the math.
183,750 cells/ml, by the way.