ELEMENTARY EXPERIMENTAL PHYSIOLOGY 175 



muscular work than the men. If hard work is frequently performed 

 with the arms the upper portion of the thorax becomes more rigid, 

 and this is an advantage, for it gives a better purchase for the contract- 

 ing muscles. 



There is no sound basis for the dogmatic teaching about thoracic and 

 abdominal breathing of some so-called specialists in physical training. 

 Healthy children do riot need lessons in breathing, but opportunities 

 for muscular exercise, for games in the open air. No reasonable 

 athlete would attempt to improve his "wind" except by training it 

 by progressively graduated runs. A good " wind " is something more 

 complex than a big or mobile chest ; it involves the heart which forces 

 the blood through the lungs. Artificial breathing exercises are unsound ; 

 healthy games and sports train the whole body, the component parts 

 of which are mutually dependent. 



At rest breathing is performed by healthy subjects with the mouth 

 closed, but during severe work it is opened instinctively and with 

 advantage, for there is then less resistance to the passage of the air 

 in and out of the chest, and the loss of heat is facilitated. 



The rate of respiration in healthy adult men at rest varies from 

 about 10 to 23 per minute : men who breathe slowly take deep 

 breaths ; those who breathe quickly take shallow breaths. 



Palpation. By placing the flat of each hand upon corresponding 

 portions of the chest it is possible to compare the movements of the 

 two sides of the thorax. If the subject be told to speak, to say 

 " ninety-nine," for example, the vibration of the voice, weal fremitus, 

 is propagated through the bronchi to the wall of the chest, and thus to 

 the hands of the examiner. 



Percussion. If a tap with the finger be given to the top of a table, 

 the note will be dull over the part directly supported by the leg, 

 but more resonant in the middle of the table. It is also easy for most 

 men to detect a difference in the sense of resistance when the tap 

 is given ; it is greater with the dull note. In a similar manner the 

 level of water in a tub can be determined. Such a method of investi- 

 gation of underlying structures is known as percussion. 



Firmly place the index finger of the left hand on the chest and tap 

 it with the middle finger of the other hand. Determine the differences 

 in note and resistance over the various parts of the thorax. On 

 the right side the resonance extends from the apex of the lung in the 

 supra-clavicular fossa to the beginning of the dulness produced by the 

 liver under the 6th rib. On the left side it extends to the cardiac 

 dulness which begins at the 4th rib. 



Make the subject take a deep breath, and then by percussion 



