144 CONSCIOUS NERVOUS OPERATIONS 



ing through the winding nasal canal, the air becomes 

 tempered before reaching the sensitive membranes of 

 throat and lungs; also much of the dust always present in 

 the atmosphere is caught by the moist mucous lining of 

 the nostrils, and the deeper air passages are protected. 



It is not necessary, in order to avoid cold, that the 

 throat should be thickly swathed in wraps of wool and 

 fur. Too much clothing about the neck causes excess of 

 perspiration there and makes the parts weak and tender. 



198. Special Training of the voice for singing or public 

 speaking should not be begun by either boys or girls 

 before the age of sixteen or seventeen, and should always 

 be attended with judgment and care against overstrain. 



199. Alcohol and Tobacco as affecting the Vocal Organs. 

 As the perfect control of the voice depends upon the 

 healthy condition of all the muscles connected with the 

 vocal apparatus, and upon the accurate adjustment of 

 nervous force to their varying needs, anything which 

 affects those muscles or the nerves affects also the voice. 

 Alcohol and tobacco do affect both. The mucous mem- 

 brane of the larynx is often much inflamed by tobacco 

 smoking, and especially by the use of cigarettes. The 

 inflammation may extend through the Eustachian tubes, 

 impairing the hearing, and into the bronchial tubes, caus- 

 ing an annoying cough. A disease known as "smoker's 

 sore throat " may result. Alcoholic beverages irritate the 

 throat and are often forbidden to those cultivating the 

 voice for singing. 



DEMONSTRATION 



71. Dissection of the Larynx. At a slaughterhouse can be obtained 

 a trachea of an ox with the larynx intact and a portion of the esoph- 

 agus ; the hyoid bone may be present also. With this material the 

 principal topics of this chapter can be illustrated. 



