RESPIRATION REST HARROW chest is altered in size chiefly by the movements of the diaphragm, and the protrusion of the abdominal wall during inspiration is therefore very marked. In men also it is the diaphragm which is chiefly operative, but the ribs are also moved. In women it is the movement of the ribs, especially the upper ones, which is the most extensive. The respiratory rhythm is the relation of the acts of in- spiration and expiration to each other as regards time. The number of respira- tions in a healthy person is about 14 or 18 per minute; it is greater (nearly dou- ble) in childhood. It varies according to circumstances, exercise, rest, health, dis- ease, etc.; in disease it may fall as low as seven or rise to 100. Though all the muscles concerned in the movements of breathing are voluntary muscles — i. e., can be made to contract by an act of will — yet respiration is nor- mally an entirely involuntary act. This is obvious from the fact that during sleep, or during absence of consciousness caused in any way, respiration goes on as well as during wakefulness. Further, though we may at will breathe or cease to breathe, yet we cannot by any effort of the will suspend the respiratory move- ments for longer than at most a few minutes at a time. History. — Aristotle (384 B. C.) thought that the object of respiration was to cool the body. He observed that the warmer the animal the more rapid the breathing, and transposed cause and effect. Galen (a. d. 131-203) experimented on the me- chanics of respiration, and knew some- thing of the nervous mechanism. He believed that "soot" and water were ex- creted from the body by the lungs. Mal- pighi (1661) described the structure of the lungs. Van Helmont (1664) discov- ered carbonic acid; Black (1757) ob- served that carbonic acid is breathed out of the body. Priestley (1774) discov- ered oxygen. Lavoisier (1776) discov- ered nitrogen, found the composition of the air, and taught that the formation of carbonic acid and water resulted from the combustion that took place in the lungs. Vogel proved the existence of carbonic acid in the venous blood; Hoff- man found oxygen in arterial blood. Magnus extracted and analyzed the gases ©f the blood in both states. Artificial Respiration. — When death is imminent owing to a cessation of the nat- ural respiration movements, it may some- times be averted by an imitation of them carried on regularly for some time. The methods fall into three divisions: (1) in- sufflation, or blowing of air into the lungs, either by the mouth or by means of bellows; (2) manual methods, in which external manipulations of the chest walls are made to effect the entrance and exit of air; (3) electrical stimulation of the respiratory muscles. In all cases where artificial respiration is required every moment is of importance. In Silvester's method the patient is laid on his back on a plane, inclined a little from the feet upward, and the shoulders are gently raised by a firm cushion placed under them, which also throws the head back. The operator then grasps the patient's arms just above the elbows, and raises them till they nearly meet above the head. This action imitates inspiration. The pa- tient's arms are then turned down, and firmly pressed for a moment against the sides of the chest. A deep expiration is thus imitated. In Howard's method the patient is laid on his back with a cushion below the middle. The operator kneels astride his hips, places his hands with fingers spread outward over the lower part of the chest wall, and alternately bends forward, throwing his weight on the^ chest to imitate expiration, and springs back to allow the elastic recoil of the chest wall to imitate inspiration. Whatever method be adopted, the move- ments must be gentle, regularly, and perseveringly carried on, at the rate of from 10 to 15 times in the minute. In all cases, but especially in that of per- sons apparently drowned, artificial res- piration should be conducted in a warm atmosphere, 90° F., or even more if pos- sible, and should be supplemented by warmth applied to the body and by vig- orous friction. In other modes of death by suffocation, such as choking or stran- gulation, the action of the heart may continue longer, and restoration to life be therefore possible after a longer de- privation of air. See Drowning. RESPIRATOR, a device for breathing through, worn over the mouth, or the nose and mouth, and secured by a ban- dage, strap, or other contrivance, to ex- clude injurious matters, such as smoke or dust, from the lungs, or to change the condition of the air by passing it through medicaments or gauze. Respir- ators are used by cutlers and other grinders to exclude the dust from the lungs, and also by firemen to prevent suffocation by smoke. Respirators for persons having weak lungs have several folds of fine wire gauze, which being warmed by the expired breath, in turn heats the inspired air. RESPONDENT, in law, the designa- tion of the party requiring to answer in a suit, particularly in a chancery suit. REST HARROW, a common Euro- pean leguminous plant, Ononis arvensit,, akin to the brooms. It is plentiful in
