194 UNCONSCIOUS NERVOUS OPERATIONS 



feeble the room may be a few degrees warmer. Sleep- 

 ing rooms should usually be much colder, but definite 

 rules cannot be given. Much depends upon habit, age, 

 and state of health. To live always in a warm atmos- 

 phere is enervating. Cold air, when pure, is far more 

 refreshing and invigorating. It is highly desirable to 

 accustom one's self to sleep with open windows in all 

 seasons. 



275. Respiration as affected by the Use of Alcohol and 

 Tobacco. The action of alcohol upon the muscular walls 

 of the arteries, which has been already more than once 

 referred to, is especially important in the capillaries of the 

 lungs. When they are dilated by the paralyzing effect 

 of alcohol, their expansion reduces the size of the air cells 

 in the lungs and leaves less room for the air which the 

 lungs need, so that less oxygen is supplied to the blood. 

 When the capillaries are often or continuously distended 

 in this way, their walls are likely to become permanently 

 thickened, and the interchange of gases which normally 

 takes place there, by which carbon dioxide passes from 

 the blood while the purifying oxygen is taken into the 

 blood, is impeded. Serious disease even may result, such 

 as a peculiar and quickly fatal form of consumption found 

 only among drinkers of alcoholic fluids. 



The throat, bronchial tubes, and lungs of a tobacco 

 smoker are all liable to irritation by the poisonous smoke, 

 and chronic inflammation is often caused. The nicotine 

 of tobacco is a deadly poison, and" in cigarettes there are 

 often other poisons equally dangerous to health. 



DEMONSTRATIONS AND EXPERIMENTS 



83. Dissection of the Respiratory Organs. The thorax of a rabbit, 

 cat, or dog will be found serviceable. Before cutting open the chest, 



