Although it takes the magnifying and resolution power of the electron microscope to visualize strands of DNA, grosser(larger) genetic structures such as chromosomes are, with proper staining, visible with the magnifications attainable with a simple compound microscope. Compound microscopes remain a valuate tool to differentiate gross genetic structure in karyotype analysis and in other studies of cellular morphology.

Optical microscopes have been in use in various forms for more than 3,000 years. The first types were extremely simple magnifiers made of globes of water-filled glass or chips of transparent crystal. Ancient Romans were known to use solid, bead-like glass magnifiers; Emperor Nero ( A.D. 37-68) often used a bit of cut emerald to augment his poor vision.

The first lenses, which were used in primitive eyeglasses, were manufactured in Europe and China in the late thirteenth century. By this time, lenscrafters realized that most clear glass...