(a) Parenchymatous Organs 38 (b) Jaundice 39 (c) Central Nervous System 39 (d) The Pregnant Uterus 39 (e) Summary 39 IV. A Comparison between the Respiratory Lesions of Influenza and those Initiated by the Inhalation of Poisonous Gases with Special Reference to:— 40 (A) The Inflammatory Response versus the Systemic Capacity to Compensate 40 (B) The Primary Injury 41 (C) The Tendency to Organization of Bronchiolar and Alveolar Exudates with Bronchiolitis and Bronchiolectasis as Sequelæ 42 (D) The Importance of the Trachea and its Ramifications as a Protective Mechanism against Infection of the Pulmonary Parenchyma 42 V. Peculiarities of the Histology of Influenzal Pneumonia 44 (A) The Extent of the Initial Pulmonary Lesion 44 (B) The Hemorrhagic Exudate—The Relation of Red to Grey Hepatization 44 (C) The Aplastic Exudate 45 (D) The Hyaline Necrosis of the Pulmonary Tissue 46 (E) The Organization Process 46 VI. Infection as a Possible Etiological Factor for Malignant New Growths 48 VII. The Bacteriology of Influenzal Pneumonia 49 (A) Organisms Associated with Influenzal Pneumonia 49 (B) The Relation of the Type of Organism to Pleural Involvement 50 (C) The Relation of Different Organisms to the Type of Pneumonia 50 (D) Summary and Discussion 54 VIII. Conclusions 55 IX. Bibliography 56 X. Illustrations 63 [Illustration: FIG. II. AUTOPSY NO. 98. DRAWING OF A SECTION THROUGH A TRACHEA SHOWING NECROTIZING HEMORRHAGIC INFLAMMATORY PROCESS OF THE MUCOSA. ] INTRODUCTION