In _anemia_ the red corpuscles are diminished and the white corpuscles and blood plaques increased in number. After excessive bleeding normal salt solution is injected, subcutaneously or by rectum, as being nearly equivalent to blood serum in composition, and the renewal of the solid elements is left to time. The length of time needed for their restoration is about a week, except in the case of the hemoglobin, which takes longer. CHAPTER IX. THE LUNGS AND RESPIRATION. Besides the heart and the great vessels the chest contains the lungs, the chief organ of respiration, which, with the rest of the respiratory system, will now be treated. The nose and mouth, through which the air first enters the body, have already been spoken of. From them the air passes through the larynx to the trachea, thence to the bronchi, and so to the lungs, where the supply of oxygen for the tissues is taken from the air by the hemoglobin of the blood. =The Larynx.=--The larynx lies in front of the pharynx at the upper and fore part of the neck, where it causes a considerable projection, known as _Adam’s apple_. It is a triangular box, base up, flattened at the back, in front, and at the sides, but becoming cylindrical below. Above it opens into the bottom of the pharynx and below into the trachea. It is lined with mucous membrane. Its opening at the base of the tongue is closed during swallowing by a little door-like valve of fibro-cartilage, the _epiglottis_, to prevent the entrance of food. Nine _cartilages_ go to make up the larynx, of which the most important are the thyroid and cricoid cartilages and the epiglottis already mentioned. The _thyroid_ is the largest and is open behind, its two alæ or wings meeting in an acute angle in front and forming the Adam’s apple, always more prominent in the male than in the female. It is attached above to the hyoid bone and has cornua or horns on either side, top and bottom. The _cricoid_ or ring-like cartilage resembles a seal ring with the stone placed posteriorly. It is stronger than the thyroid and forms the lower part of the cavity of the larynx. Inside and resting on the upper border of the cricoid are the two smaller _arytenoid_ or pitcher-like cartilages, pyramidal in shape, and surmounting these again the two _cornicula laryngis_. The two _cuneiform cartilages_ are in the free borders of the folds of mucous membrane which extend from the apex of the arytenoids to the sides of the epiglottis. Numerous small muscles serve to bind these various cartilages together.