TYPES OF RESPIRATION. 375 



bringing into play all the muscles and other forces available, there 

 still remains a volume of air which cannot be forced out ; this is 

 the residual air, and has been estimated by Sir Humphrey Davy to 

 be 674 c.c. It has been measured by different observers upon 

 both the living and the dead body. In one set of observations 

 upon 9 corpses, the minimum was 640 c.c., the maximum, 1231 

 c.c., the mean, 981 c.c. In another series of observations on living 

 males the results were 440 c.c. minimum, 1250 c.c. maximum, 

 and 796 c.c. mean ; and in still another upon living females, 347 

 c.c. minimum, 526 maximum, and 478 c.c. mean. Neupauer 

 determined the amount of residual air in a living subject to be 

 very much greater. 



Vital capacity is the volume of air over which an individual 

 can exert control. It is the amount which he can expel by a 

 forced expiration after having taken a forced inspiration ; it is, 

 therefore, the sum of the tidal, complemented, and supplemental 

 air ; it excludes the residual air. Hutchinson gives it as 3558 c.c., 

 basing his estimate on 1923 observations. 



The vital capacity of the newborn child is about 120 c.c. 



Although it is impossible to give any figures which will repre- 

 sent measurements that are necessarily so variable as those just 

 given, still it may be of use to have an approximate estimate for 

 purposes of reference ; and we may place the amount of tidal air 

 at 300 c.c., complemental air at 1500 c.c., reserve air at 1500 c.c., 

 and residual air at 1000 c.c. 



Frequency of Respiration. In the newborn child the 

 number of respirations per minute is 44 ; at five years of age, 26 ; at 

 twenty years, 20 ; at thirty years, 1 6 ; and at fifty years, 18. These 

 figures represent an average during a quiescent condition. Should 

 the respirations be counted during sleep, they would be 1 or 2 less 

 per minute ; during great activity they would be increased con- 

 siderably, in the adult running up to 30 or more. 



TYPES OF RESPIRATION. 



It has been the practice among writers on physiology to speak 

 of the superior costal or female type of respiration and the 

 abdominal, inferior costal, or male type. The following condensed 

 statement from one of the best text-books on this subject represents 

 the views of these writers : " In children, as well as in the adult 

 male, under ordinary conditions, the diaphragm performs most 

 of the work, and the movements of the abdomen are the only 

 ones especially noticeable .... In the female the movements 

 of the chest, particularly of its upper half, are habitually more 

 prominent than those of the abdomen, and this difference in the 

 mechanism of respiration is characteristic of the sexes." The 

 protrusion of the abdominal wall, caused by the descent of the 



