Summary: The pathology of emphysema is described in the book, focusing on the enlargement of air spaces in the lungs. The historical descriptions by Laennec and Baillie are discussed, highlighting the mutual dependence of various types of emphysema. The definition of emphysema is explored by different authors, with a consensus on the increase in the size of air spaces. The conflicting diagnoses arising from different examination methods have led to a search for a more sophisticated anatomical definition. The text also delves into the radiological aspects of emphysema and the physiological attempts to define the condition. Additionally, cases of chronic bronchitis with associated emphysema and right ventricular hypertrophy are examined in detail, emphasizing the impact on respiratory function and clinical outcomes. The book provides a comprehensive overview of the classification and pathogenesis of various forms of emphysema, shedding light on the complexities of this chronic lung disease.