These were simply placed on a slide with a drop of water. I did not use a cover slip because I did not want to crush them (and I was too lazy to use the technique I might normally employ... Vaseline spots at the four corners of a slip
). Also, since these were active, I thought perhaps as the water evaporated to the point where they were just barely covered they might become less mobile. The first shot was frustrating in that I needed to do a stack, and the water was still a little too deep to inhibit their motion. While these amoeba don't move around rapidly, they move enough to make obtaining a stack tricky (especially when there are 4 of them). What I did was to take a short HD video clip while running the focus from top to bottom. I extracted the individual frames and stacked them. Quality is not all that bad, but not what can be done if everyone would hold still!
The second shot was with a 20X and DIC. Here the water level was just barely below the top of the tests and I was able to shoot a stack in the conventional manner. My 20X is not really a happy performer without a 0.17 cover slip, (and the uneven water surface causes some weird effects as well), but it did OK.
[ah, DIC cuts right through it?]