I've acquired a very good microscope and my vet is excited that I am trying to do it myself. He gave me a few slides but I also understand that I need a coverslip for the slides. I'm unsure just what I need. Should they be glass like the slides or can they be plastic as well. The solution is easy to make if you follow directions so that is not a problem. I just need to know about what the cover slips should be like. Square, same size as the slide or round? I'm not sure what is best for examining a specimen.