\yO TIME OCCUPIED BY THE RESPIRATORY MOVEMENTS. 



ratio for an adult is as 6 to 7 ; in women, children, and old people, 6 to 8 or 6 to 

 9. Vierordt found the ratio to be 10 to 14*1 (to 24-1); J. R. Ewald, 11 to 12. 

 It is only occasionally that cases occur where inspiration and expiration are equally 

 long, or where expiration is shorter than inspiration. When respiration proceeds 

 quietly and regularly, there is usually no pause (complete rest of the chest-walls) 

 between the inspiration and expiration. The very flat part of the expiratory curve 

 has been wrongly regarded as due to a pause. Of course, w r e may make a volun- 

 tary pause between two respirations, or at any part of a respiratory act. 



Some observers, however, have described a pause as occurring between the end of expiration 

 and the beginning of the next inspiration (expiration pause), and also another pause at the end 

 of inspiration (inspiration pause). The latter is always of very short duration, and consider- 

 ably shorter than the former. During very deep and slow respiration, there is usually an 



Fig. 137. 

 Pneumatograms obtained by means of Kegel's stethograph. I, normal curves ; II, curve from 

 a case of emphysema ; a, ascending limb ; b, apex ; c, descending limb of the curve. The 

 small elevations are due to the cardiac impulse. 



expiration pause, while it is almost invariably absent during rapid breathing. An inspiration 

 pause is always absent under normal circumstances, but it may occur under pathological 

 conditions. 



In certain parts of the respiratory curve slight irregularities may appear, which are sometimes 

 due to vibrations communicated to the thoracic walls by vigorous heart-beats (fig. 137). 



The u type " of respiration may be ascertained by taking curves from various 

 parts during the respiratory movements. Hutchinson showed that, in the female, 

 the thorax is dilated chiefly by raising the sternum and the ribs (Respiratio costalis), 

 while in man it is caused chiefly by a descent of the diaphragm (Respiratio 

 diaphragmatica or abdominalis). In the former, there is the so-called " costal type," 

 in the latter the " abdominal or diaphragmatic type." 



This difference in the type of respiration in the sexes occurs only during normal quiet 

 respiration. During deep and forced respiration, in both sexes the dilatation of the chest is 

 caused chiefly by raising the chest and .the ribs. In man, the epigastrium may be pulled in 

 sooner than it is protruded. During sleep, the type of respiration in both sexes is ^thoracic, 



