“The structural changes induced by habitual use of alcohol and the action of this agent on the pepsin, seriously impair the digestive power.  Hence it is, that those who are habitual consumers of alcoholic fluids suffer from disorders o digestion.”—­Robert Bartholow, recently Professor of Materia Medica in the University of Pennsylvania.

“Alcohol in any appreciable quantity diminishes the solvent power of the gastric fluid so as to interfere with the process of digestion instead of aiding it.”—­Professor W. B. Carpenter, the eminent English physiologist.

[29] “Cirrhosis of the liver is notoriously frequent among drunkards, and is in fact almost, though not absolutely, confined to them.”—­Robert T. Edes, formerly Professor of Materia Medica in Harvard Medical College.

“Alcohol acts on the liver by producing enlargement of that organ, and a fat deposit, or ‘hob-nailed’ liver mentioned by the English writers.”—­Professor W. B. Carpenter.

[30] Preparation of Artificial Gastric Juice. (a) Take part of the cardiac end of the pig’s stomach, which has been previously opened and washed rapidly in cold water, and spread it, mucous surface upwards, on the convex surface of an inverted capsule.  Scrape the mucous surface firmly with the back of a knife blade, and rub up the scrapings in a mortar with fine sand.  Add water, and rub up the whole vigorously for some time, and filter.  The filtrate is an artificial gastric juice.

(b) From the cardiac end of a pig’s stomach detach the mucous membrane in shreds, dry them between folds of blotting-paper, place them in a bottle, and cover them with strong glycerine for several days.  The glycerine dissolves the pepsin, and on filtering, a glycerine extract with high digestive properties is obtained.

These artificial juices, when added to hydrochloric acid of the proper strength, have high digestive powers.

Instead of (a) or (b) use the artificial pepsin prepared for the market by the wholesale manufacturers of such goods.

[31] The cause of the clotting of blood is not yet fully understood.  Although the process has been thoroughly investigated we have not yet a satisfactory explanation why the circulating blood does not clot in healthy blood-vessels.  The ablest physiologists of our day do not, as formerly, regard the process as a so-called vital, but a purely chemical one.

[32] Serous Membranes.—­The serous membranes form shut sacs, of which one portion is applied to the walls of the cavity which it lines; the other is reflected over the surface of the organ or organs contained in the cavity.  The sac is completely closed, so that no communication exists between the serous cavity and the parts in its neighborhood.  The various serous membranes are the pleura which envelops the lungs; the pericardium which surrounds the heart; the peritoneum which invests the viscera of the abdomen, and the arachnoid in the spinal canal and cranial cavity.  In health the serous membranes secrete only sufficient fluid to lubricate and keep soft and smooth the opposing surfaces.