THE PH YSIOL OGY OF THE NER VO US S YSTEM 209 



1. Appliances. Glass rod, 20 cm. long, with rounded ends; 

 3 per cent, carbolic acid; beaker of water; towel; bristle mounted 

 in handle. 



2. Observations, (a) Respiratory Reflexes. (1) Make a bristle 

 aseptic. Let one member of the group act as subject. Let the sub- 

 ject close his eyes. The observer should introduce the bristle very 

 gently through the nostril, and, as far as possible, up the nasal 

 passage. The response will probably be in the form of a sneeze. 



Accidental introduction of irritating substances into the respiratory 

 passages below the glottis causes coughing. 



(2) Make a bristle aseptic and bend it into a semicircle. Let 

 the subject open the mouth wide, depress the tongue, and say "Ah!" 

 prolonging the sound several seconds. Introduce the bristle into 

 the mouth; pass it over the tongue without touching the latter; turn 

 the point downward back of the tongue, and tickle the glottis. A 

 convulsive, reflex movement of the larynx, sometimes accompanied 

 by a cough, will result. 



(6) Circulatory Reflexes. (3) Posture influences the circulation 

 reflexly. Let the subject remain sitting quietly while the pulse is 

 counted through a minute. Note the number. Let the subject lie 

 on the back upon the table. After he has rested quietly three to 

 five minutes, take the pulse rate again. Let the subject stand and 

 observe the rate after three to five minutes. 



(4) Respiration influences the circulation reflexly. Let the sub- 

 ject sit breathing at the rate of thirty respirations per minute for two 

 minutes. Count the pulse during the second minute. Let the sub- 

 ject then drop to ten respirations per minute for three minutes, and 

 then slower, if possible, during the fourth minute, when the pulse is 

 to be counted. 



(5) Exercise influences the circulation reflexly. This has already 

 been demonstrated. (See Circulation.) 



(c) Secretory Reflexes. (6) The chewing of anything like paraffin 

 or rubber incites reflexly the free flow of saliva. In a similar way the 

 presence of food in the stomach and intestines stimulates the secre- 

 tory activity of the digestive glands. 



(d) Reflexes of Deglutition. (7) Let the subject open the mouth. 

 Introduce the aseptic glass rod into the mouth without touching 

 tongue or cheeks. Gently touch the uvula; it will probably rise. 

 Touch the fauces, and observe the convulsive swallowing move- 

 ment. Sometimes this merges into a gagging movement. 



The raising of the uvula is part of a normal swallowing act. The 

 response of the fauces may be a part of an act of swallowing, or of 

 a protective act (gagging), according to the conditions of the stimu- 

 lation. 



(e) Visual Reflexes. (8) Let the subject direct his vision toward 

 some distant object. Make a sudden movement with hand or a book 



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