II. Blue type of asphyxia from phosgene poisoning, with intense venous congestion. III. Pallid type of asphyxia from phosgene poisoning, with circulatory failure. IV. Gangrene of foot caused by vascular thrombosis from chlorine poisoning. V. Erythema of skin from general exposure to the vapour of Yellow Cross substance. VI. Blistering of buttocks by mustard gas. VII. Burning of scrotum and penis by mustard gas. VIII. Brown staining from mustard gas. IX. Ulceration of trachea by mustard gas. X. Microscopic section of human lung from mustard gas poisoning, with death at end of second day (40 hours). XIA. Severely burned eye in the acute stage. XIB. Slightly later stage of acute burning. XIIA. Stage of resolution after severe burning. XIIB. Late stage of resolution. XIIIA. Drawing of the cornea in the acute stage of severe burning. XIIIB. Drawing of cornea in the stage of resolution after severe burning. PLATE NO. I Microscopic section of human lung from phosgene shell poisoning. Death at the nineteenth hour after gassing. The piece of lung shown is almost entirely useless for aeration of the blood. Most of the pulmonary alveoli are filled with oedema fluid, and the walls of the air sacs are burst asunder in many places. The rounded edges of these torn walls can be recognized both in the areas of emphysema and in the parts that are flooded with oedema fluid. The bronchus also is filled with oedema fluid, but it should be noted that its lining epithelium is intact and pus cells have not accumulated in the secretion. The blood vessels of the alveolar network are congested; and intravascular thrombosis is frequently found in these smaller vessels, though it is not actually shown in the area of this section. The main changes in the lung are: Congestion, and occasional thrombosis, of the network of pulmonary blood vessels. Abundant outpouring of inflammatory oedema fluid both into the tissues and into the air spaces of the alveoli and bronchi. Disruptive emphysema of the weakened lung tissue. The result of these changes is that the blood circulation through the lungs is impeded, and the respiratory exchange of gasses between the blood and the air in the lung is seriously diminished. The gassed man is in danger of death by asphyxia so long as his lung is drowned in oedema fluid. From the third day onwards the oedema fluid is reabsorbed or expectorated, and the lung soon resumes its functions. Bronchopneumonic complications may develop from secondary infections, but they are not very common.