26 Physiology. 



especially in forced expiration, as after violent exercise and 

 in coughing. The abdominal wall consists of several layers 

 of muscle. 



Muscles of Expression. The facial expression is due 

 to the action of the muscles of the face, which in turn are 

 under control of the cranial nerves. The habitual position 

 becomes somewhat " fixed," so it is true that character is 

 often shown by "the looks." Cultivation of happy thoughts 

 therefore tends to make one better looking. 



Muscles and Fat. Fat fills in space between muscles, 

 and, if abundant, forms a layer over the muscles. One 

 notable instance is the hollow triangular space between 

 the muscles of the cheek. If there is very little fat, a 

 depression is seen, forming the "hollow cheeks." But an 

 abundance of fat makes a corresponding elevation. 



Convulsions. These spasmodic actions are due to dis- 

 ordered action of the muscles, and to a disturbed action 

 of the nervous system that controls the muscles. Various 

 disturbances, such as indigestion, may by reflex action 

 bring on convulsions. 



Alcohol and Muscular Energy. Alcohol does not in- 

 crease the energy of the body for muscular work. Re- 

 peated experiments have been made which show that 

 power to do muscular work is diminished as the result 

 of taking alcohol. The person may, and often does, feel 

 stronger, but the feelings are neither a sure test nor a 

 safe guide. As one writer says, the drunken man thinks 

 he is strong enough to hold two men, whereas he needs 

 two men to support him in his weakness. Test of ability 

 to do work shows the weakening effect of alcohol. It was 

 formerly supposed that when men were called upon to 

 perform unusually hard work they needed the sustaining 



