This booklet is one of a series on various ophthalmologic subjects of current interest. Francis Bigar (Zurich) presents a monograph of 94 pages on "Specular Microscopy of the Corneal Endothelium" in which he describes instrumentation and his modifications to obtain sharper contrast, reduction of the corneal surface light reflection, and a larger field. He stresses qualitative interpretation, including cell borders, size, shape, and intracellular vacuoles. Because of the nonhomogeneity of endothelial cells within a 0.25-sq mm area, a larger area up to 1.5 sq mm and several photographs in different areas are necessary to obtain a better quantitative assessment. From personal observations, he found that the endothelial cell count fell from more than 3,000 cells per square millimeter in early years to approximately 2,500 cells per square millimeter at the age of 30 years, and thereafter fell less rapidly. Although acute angle-closure glaucoma reduced the endothelial density greatly, this was