Genes is a 120-page discussion of six different definitions of gene, ranging from the purely molecular to the nearly metaphysical. Slack (emer., biology, Univ. of Bath, UK) covers an amazing amount of material in very few words and, consequently, provides very little background information and few references. The level of detail is somewhat uneven, with classical genetics and molecular biology receiving the most emphasis and featuring the most examples. The explanations and figures are good enough to remind readers of facts and concepts, but readers learning the material for the first time will be lost. Although the writing is generally good, the text contains many punctuation errors. The major value of the book is that it juxtaposes historical, molecular, cellular, organismal, evolutionary, and behavioral domains in one volume, so readers familiar with one or more of these areas can examine the concept of the gene through multiple lenses. Genes assumes a fair amount of prior knowledge in readers, but it provides a panoramic view of one of the great concepts of 20th-century science. Summing Up: Recommended. Upper-division undergraduates through professionals/practitioners. --Roger M. Denome, MCPHS University