Learn how bacteria can take hold in living plants and what that means for crops and health. See how scientists studied infection, spread, and plant defenses. This edition, drawn from Erwin F. Smith’s classic work, examines how disease-causing microbes can exist inside growing plant tissues. It explains how the uninjured leaf surface stops invasion, while wounds and growing tissue can open a doorway for bacteria to multiply. Readers will gain a clear view of the early experiments that showed certain animal-pathogenic bacteria can live and multiply in plants, the conditions that support or hinder this process, and how plant tissue responses reveal clues about infection. How bacteria enter and move within plant tissues, and the impact of plant age and tissue type. - The role of mechanical injury in allowing pathogens to establish inside plants. - Observations on specific bacteria, their growth patterns, and the signs they leave on leaves and stems. - Methods used to test infection, including inoculation, culture growth, and animal challenges. Ideal for readers interested in plant pathology history, microbiology, and how scientists linked plant diseases to microbes long before modern genetics.