• • Xll CONTENTS. between arterial and venous blood. Cause of the changes of colour which the blood undergoes. Experiments. Gases contained in the blood. Influence of the salts in ' producing the colour of the blood, ...... 302-306 Chap. V.—Of the chemical process of respiration.—Conditions on which the pro- cess depends. The different theories to explain the process. Products of respira¬ tion in hydrogen and nitrogen. Source of the carbonic acid evolved during respira¬ tion. * Carbonic acid evolved from the skin, .... 306-315 Chap. VI.—Of the respiratory movements and the respiratory nerves.—a. The movements of respiration.—Movements of the thorax. Of the larynx and fauces. Contractility of the lungs and bronchi, b. Of the influence of the nerves on the function of respiration.—Source of the nervous influence for the respiratory move¬ ments. Sir C. Bell’s views. Sympathetic affections of the respiratory muscles,— coughing, vomiting, &c. Cause of the respiratory movements. Effects of division of the vagus nerves, ....... 316-327 SECTION II.—Of Digestion, AND ChYLIFICATION. Chap. I. Of digestion in general,—The food. Most simple nutritive substances, vegetable and animal. Nutritive principle of food. Azotised and unazotised ali¬ ments. Necessity of a varied diet. Dr. Prout’s classification of alimentary sub¬ stances. Sensations connected with digestion, appetite, and satiety, &c. Hunger and thirst. Effects of long fasting, ..... 328-338 Chap. II.—Of the digestive organs.—a. Of the different forms of the alimentary canal.— In the Invertebrata. In the Vertebrata. Influence of the nature of the food on the organisation, b. Of the coats of the alimentary canal.—The mucous membrane,—its glands. The muscular coat. The serous coat, . . 338-349 Chap. III.—Of the movements "of the alimentary canal.—1. Deglutition,—its three stages. Influence of tne epiglottis in deglutition. 2. Movements of the oesophagus. 3. Stomach during digestion. 4. Rumination. 5. Vomiting. Mode of action of emetics. 6. Motions of the intestines, ..... 349-360 Chap. IV.—Of the secretions poured into the digestive canal.— The saliva,—its chemical composition. The gastric juice.—Its analysis. The bile,—biliary canals of insects. Is the bile secreted from venous or from arterial blood? Its properties and chemical composition. Bile of serpents, fishes, &c.,—discharge of the bile. The pancreatic juice,—its composition. Secretion of the intestines, . 361-376 Chap. V.—Of the changes which the food undergoes in the alimentary canal.— а. Change effected by the saliva, b. Change effected in the stomach,—action of the gastric juice.—Dr. Beaumont’s observations. Table showing the time required for the digestion of different kinds of food. Gas of the stomach. Composition of the chyme. Digestion in ruminants,—in birds. Theory of digestion,—theory of fer¬ mentation. Theory of Schultz. 1. Is there a gastric juice? 2. Is the gastric juice a solvent for food out of the body? Experiments of Spallanzani, Tiedemann and Gmelin, Dr. Beaumont, and others. 3. Are the solvent principles in the gastric juice acids, or other unknown substances? Experiments of Tiedemann and Gmelin, and Beaumont. Of Müller. Researches of Eberle, Müller, and Schwann. Artificial digestive fluid. Chemical properties of the digestive principle, or “pepsin.” Its action on casein. Substances not dissolved by the “ pepsin.” Influence of the nerves and of electricity on digestion, c. Of the changes which the chyme undergoes in the small intestine.—Influence of the bile on the chyme. Effects of ligature of the bile duct. d. Changes which the ingesta undergo in the large intestine.—Gaseous matters in the intestines. The feeces, ..... 376-403 Chap. VI.—Of chylification.—Absorption of the chyle. Properties of the chyle. Differences in the chyle, arising from variety of food. The chyle globules,—cause of the white colour of the chyle. Its red colour. The fibrin of the chyle—its source. The serum,—its composition. Comparison of the chyle with lymph,—with blood. Effect of ligature of the thoracic duct, .... 403-412 Chap. VII.—Of the function of the spleen, the supra-renal capsules, the thyroid, and the thymus glands.—a. The spleen,—its structure. Function of the spleen. б. The supra-renal capsules,—their structure. Function of the supra-renal capsules. c. The thyroid body,—its structure, d. The thymus gland,—its structure. Function of the thymus, ........ 412-417 SECTION III.—Of Secretion. Chap. I.—Of the secretions in general.—Distinction of secretions and excretions. The secretions divided into two kinds. Secreting apparatus.—Secreting cells. The