[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.
[33] A correct idea may be formed of the arrangement of the pericardium around the heart by recalling how a boy puts on and wears his toboggan cap. The pericardium encloses the heart exactly as this cap covers the boy’s head.
[34] “Alcohol taken in small and single doses, acts almost exclusively on the brain and the blood-vessels of the brain, whereas taken in large and repeated doses its chief effects are always nervous effects. The first effects of alcohol on the function of inhibition are to paralyze the controlling nerves, so that the blood-centers are dilated, and more blood is let into the brain. In consequence of this flushing of the brain, its nerve centers are asked to do more work.”—Dr. T. S. Clouston, Medical Superintendent of the Royal Asylum, Edinburgh.
“Alcoholic drinks prevent the natural changes going on in the blood, and obstruct the nutritive and reparative functions.”—Professor E. L. Youmans, well-known scientist and author of Class Book of Chemistry.
[35] The word “cell” is not used in this connection in its technical signification of a histological unit of the body (sec. 12), but merely in its primary sense of a small cavity.
[36] “The student must guard himself against the idea that arterial blood contains no carbonic acid, and venous blood no oxygen. In passing through the lungs venous blood loses only a part of its carbonic acid; and arterial blood, in passing through the tissues, loses only a part of its oxygen. In blood, however venous, there is in health always some oxygen; and in even the brightest arterial blood there is actually more carbonic acid than oxygen.”—T. H. Huxley.
[37] “Consumption is a disease which can be taken from others, and is not simply caused by colds. A cold may make it easier to take the disease. It is usually caused by germs which enter the body with the air breathed. The matter which consumptives cough or spit up contains these germs in great numbers—frequently millions are discharged in a single day. This matter spit upon the floor, wall, or elsewhere is apt to dry, become pulverized, and float in the air as dust. The dust contains the germs, and thus they enter the body with the air breathed. The breath of a consumptive does not contain the germs and will not produce the disease. A well person catches the disease from a consumptive only by in some way taking in the matter coughed up by the consumptive.”—Extract from a circular issued by the Board of Health of New York City.
[38] “The lungs from the congested state of their vessels produced by alcohol are more subject to the influence of cold, the result being frequent attacks of bronchitis. It has been recognized of late years that there is a peculiar form of consumption of the lungs which is very rapidly fatal and found only in alcohol drinkers.”—Professor H. Newell Martin.
[39] “The relation to Bright’s Disease is not so clearly made out as is assumed by some writers, though I must confess to myself sharing the popular belief that alcohol is one among its most important factors.”—Robert T. Edes, M.D.
[40] Thus the fibers which pass out from the sacral plexus in the loins, and extend by means of the great sciatic nerve and its branches to the ends of the toes, may be more than a yard long.
[41] Remarkable instances are cited to illustrate the imperative demand for sleep. Gunner boys have been known to fall asleep during the height of a naval battle, owing to the fatigue occasioned by the arduous labor in carrying ammunition for the gunner. A case is reported of a captain of a British frigate who fell asleep and remained so for two hours beside one of the largest guns of his vessel, the gun being served vigorously all the time. Whole companies of men have been known to sleep while on the march during an arduous campaign. Cavalrymen and frontiersmen have slept soundly in the saddle during the exhausting campaigns against the Indians.