968. Lymph contains in solution more animal matter than chyle, and the white globules are more abundant in lymph. But though lymph contain in solution more albumen and fibrin than chyle, it is not so richly loaded with these substances as blood. Still, however, the solution of albumen and fibrin in lymph approximates lymph so closely to the blood, that the lymph very much resembles the clear liquor sanguinis of which the blood consists when the red particles are abstracted from it. The colourless liquor sanguinis is the lymph of the blood. Lymph is blood without red particles; and blood, lymph with red particles. 969. The chyle is transmitted into the lymph-vessels to mingle with the lymph before it flows into the veins to mingle with the blood. 970. The commingled fluids, chyle and lymph, pass into the blood very slowly, drop by drop. The regulation of the rapidity of the admixture seems to be the chief office of the valve placed at the termination of the thoracic duct. When the operation is observed in a living animal, it is seen that this valve prevents the new matter from flowing into the blood in a full stream. If in a dog of ordinary size that has recently eaten as much animal food as it chose, the thoracic duct be opened in the neck, the dog being alive, there will flow from the duct about half an ounce of fluid in five minutes (831); yet when this fluid reaches the termination of the duct only a few inches further on, it flows into the vein only drop by drop, at considerable intervals. One great object of pouring the chyle and lymph into the venous system so close to the heart (fig. CLXXVIII.), and of causing the commingled fluid to pass under the action of that powerful engine before it is transmitted to the lungs, seems to be, by the agitation to which it is subjected in the right auricle and ventricle to accomplish the most perfect admixture possible between the particles of the chyle and lymph and the red particles of the venous blood; an object which would be counteracted by the too rapid entrance into the current of the circulation of the new and as yet imperfectly assimilated matter. 971. After their due admixture by the powerful action of the engine that works the circulation, the commingled fluids are transmitted by the right heart to the lungs. There the watery portion of the chyle and lymph is removed; the composition of the albumen and fibrin is completed, these substances being changed from a weak and loose into a strong and concentrated state; the solid particles are increased in number, augmented in size, and changed from a white into a red colour; carbon is given off; oxygen is absorbed; azote is alternately inhaled and exhaled; and the ultimate result is, that the three fluids—chyle, lymph, and venous blood—are converted into one homogeneous fluid, arterial blood, the proper nutrient fluid.