In the infant and young child the walls of the thorax are exceedingly yielding and elastic. This is because the greater portion is made up of cartilaginous tissue before the completed ossification of the bony structures has taken place. The thoracic muscles are imperfectly developed. This makes the thoracic walls very thin. In well nourished infants the walls are made thicker by the abundance of fat which is found deposited on them. The diaphragm is very high in the infant and this greatly decreases the capacity of the thorax as well as does the frequent distention of the stomach and intestinal tract because of the accumulation of gas. The trachea and bronchi of the infant are comparatively larger than in the adult, the air cells are much smaller, and for this reason a slight acute congestion will interfere almost as much with their function as will hepatization. This necessitates immediate action in all conditions which involve the respiratory tract, and especially those which affect the lungs or bronchi. In all such cases results are obtained very quickly under adjustments. In the child there is a greater tendency for the inflammation to spread in the lung tissue than in an adult. ACUTE CATARRHAL BRONCHITIS There is probably no one acute incoördination affecting infants and children that is so common as acute catarrhal bronchitis, commonly called cold in the chest. During the cold months, and especially in the late winter and early spring, there are a great many cases. The chiropractor who is careful in handling these incoördinations will find no class of cases that will give more satisfactory results. The analyzing must be done very carefully and the vertebrae must be moved from the very beginning because if results are not obtained quickly the inflammation will spread to the air vesicles very rapidly. When this occurs there is danger of serious complications. Symptoms In the more mild form of bronchitis the symptoms develop rather gradually and the first noticed may be a coryza or nasal catarrh. As the bronchi become involved there will be a slight rise in the temperature, noticeably increased respiration, and a slight cough. There may be restlessness, anorexia and vomiting, usually caused by swallowing the mucous that is coughed up. Rales are heard over the entire chest. These appear very early and may remain for some little time after all other symptoms have disappeared. It is very common to hear coarse rales with a very slight cold in the young infant.