OK, I'm getting a better idea how to feed sample into the hemocytometer (I've been spelling that wrong for about 2 years!).
The coverslip goes on first, then use pipette to drop sample just outside the slip, and the sample capillaries into the 0.1mm channel between the cover slip and the grid. Here, I took another pic at 400x where you can see some of the grid lines. Each of these small boxes is 0.05mm across (0.0025mm^2). 16 of them make up the actual area you have to count (i.e., in the picture below you see half of the squares I counted).
Count all 16 squares, multiply x 250,000, and you have cells per ml. You also need to multiply by any dilution ratio (this was 25:1). In the example below, I counted 61 cells in the full 16 squares. 61 x 250,000 x 25 = 381.25 million cells per milliliter. Easy peezy. Now to determine how many are alive!
A lot of the tutorials have you continue counting blocks, essentially getting the count in the larger 25 blocks in the middle. Then they multiply by 10,000 instead of 250,000. As long as you understand the dimensions of each block, and know that there are 1000 cubic mm in 1 ml, you'll figure out the math.
