Scientists whose passion for research motivated them to use their own bodies in a quest for answers make high-interest subjects for this compelling volume. The element of danger that each voluntarily faced, which sometimes resulted in injury or death, prompts a cautionary sentence in the book’s introduction that discourages readers from taking risks with their own bodies (“leave the medical self-experiments to professionals”). Vivid details of Lazzaro Spallanzani’s exploration into the workings of the digestive tract make it hard to imagine anyone wanting to follow in his footsteps, however. His research required him to swallow a wooden tube filled with food and enclosed in a linen bag. He then examined the contents of the tube after it had passed through his body. He seemed unfazed, however, and reported that the package “exited happily at the end of 22 hours.” His digestive juices did their job, and this self-inflicted investigation furthered scientific understanding of a bodily function. Spallanzani’s chapter is one of ten stories presented, spanning research of men and women from six different countries, from the late 1700s to the present day. The scientists highlighted share a bold, pioneering attitude and a willingness to risk all in the pursuit of knowledge. (Ages 10–15)