752 



CHMMISTR Y OF RESPIRA TION. 



There is an irregular increase of the vital capacity 

 regards age there is an increase from 15 to 35 years, 



FIG. 68. Hutchinson's spirometer. 



with weight, and as 

 and then a decrease 



from 35 to 65 years, even when height is 

 taken into consideration. When a man is 

 standing, his vital capacity is 260 cub. in. ; 

 in sitting erect, recumbent, and prone posi- 

 tions, it is 255, 230, and 220 cub. in. 

 respectively. 



On the opposite page the average 

 amounts of complements!, tidal, reserve, 

 and residual air are given, but it is 

 necessary to point out again that they are 

 only Approximate values. The several 

 volumes have already been shown to vary 

 considerably in different individuals. 



Hermann 1 subdivides the residual air 

 into collapse air, the quantity driven out of 

 the lungs when the thorax is opened ; and 

 the minimal air, the quantity which re- 

 mains in the collapsed lungs. 



In newly-born children the volume of 

 each inspiration in quiet breathing is 35 c.c., 

 but during screaming it is raised to 61 c.c.; 

 the vital capacity is about 120 c.c. The 

 volume of the lungs of four children born 

 dead at full term was 40, 55, 55, and 60 c.c. 

 respectively, and when blown out they con- 

 tained 25, 30, 50, and 90 c.c. of air respect- 

 ively. 2 For the first few days of life the 

 lungs completely fill the opened thorax; 

 there is no collapse air ; the residual air is 

 the minimal air. The lungs during each 

 expiration become almost free from air, and 

 the ventilation is very great, the renewal 

 of air being almost perfect. 3 



For the determination of the volumes 

 of air present in the lungs under different 

 conditions, Hutchinson used a special 

 meter, which he termed a spirometer. The 

 construction of this apparatus is shown in 

 Fig. 68. 4 



Since that time many simpler and 

 improved forms of spirometer have been 

 introduced. 5 The most important precau- 

 tion is to reduce the resistance of the meter 

 as much as possible, otherwise the depth 

 and frequency of respiration become ab- 

 normal. 



1 "Lehrbucli der Physiol.," Berlin, 1896, Aufl. 11, S. 126. 



2 Eckerlein, Ztschr. f. Gcburtsh. u. Gynak., Stuttgart, 1890, Bd. xix. S. 120. 



3 Hermann, loc. cit., S. 127. 



4 For further details, see Hutchinson, article "Thorax," Todd's "Cyclopaedia of 

 Anatomy and Physiology," vol. iv. p. 1069. 



5 Fleischl von Marxow, CentralbL /. Physiol., Leipzig u. Wien, 1888, S. 39 ; Clar, 

 Wien. Tclin. Wchnschr., 1889, No. 18 ; Marcet, " Proc. Physiol. Soc." Journ. Physiol., Cam- 

 bridge arid London, 1897, vol. xxi. ; Hanriot and Richet, Compt. rend. Soc. de biol., Paris. 

 1887, p. 405. 



