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46


11 11 11


J,




40°





39


11 si-v ,,


) )


11 . . .







37


, , two , ,


Paul Bert.


Pigeon




1


16


,, five ,,


) )


Hen . . . .




3


31


, , six , ,


; 9


Duck ....




11


17


eight


))



The practical importance of these experiments in connection with
the cases of suspended animation in children at birth, and in adults
after drowning, is obvious.^



The Exchange of G-ases between the Blood and the Am in
THE Lungs — External Eespikation.

The mechanism of the ventilation of the lungs is described in
another part of this work;^ here it is necessary only to discuss the
frequency and volume of inspiration and expiration, the capacity of the

1 This article, ]>. 713. See also "Animal Heat," this Text-book, vol. i. p. 865.
- "Report of tlie Royal Humane Society," 1865, p. 31.
^ "Mechanism of Respiration," this Text-book, vol. ii.



FREQ UENC V OF RESPIRA TION IN MAN.



1\1



lungs, and other factors which bear upon the composition of the air in
the lungs.

The frequency of respiration in man. — Under normal conditions
this could be readily and exactly determined, were it not liable to
variations as soon as the attention of the subject is directed to the
breathing. Apart from this, the most important causes of variations
in the frequency of respiration are age, exercise, and temperature.

Age. — The frequency of breathing decreases from birth to old age,
as shown by the following table, the result of three hundred observations
made by Quetelet^ upon human subjects of the male sex.



Age.


EEsriEATioNS PER Minute.


Maximum.


Minimum.


Mean.


Xewly-born
5 years
15-20 ,,
20-25 „
25-30 ,,
30-50 ,,


70
32
24
24
21
23


23

16

14
15
11


44

26

20

18-7

16-0

18-1



In liealtliy infants the respiration is very irregular in frequency,
and often of the Clieyne- Stokes type.-

The average frequency of respiration in 1897 adult males was found
by Hutchinson ^ to be 20 per minute, one-third of the cases breathed
at that rate, and 1731 between 16-24 per minute.

Exercise increases not only the frequency but also the depth of
breathing. This hyperpnoea is not due to a deficiency of oxygen or an
accumulation of carbon dioxide in the blood, but probably to some pro-
duct which is derived from the metabolism in the muscles, and stimulates
the respiratory centre.^

The physiological explanation of the condition, well known to athletes as
" second wind," appears to be unknown ; during violent exercise, such as
running or rowing, there is, after a time, considerable dyspnoea, but if the
exercise be continued this discomfort disappears, sometimes quite suddenly ;
the man has now got his " second wind," and can continue the exertion in com-
parative comfort. The dyspnoea in these cases appears to be partly cardiac,
for the pulse-rate may be more than doubled, but when the "second wind" is
obtained, there appears to be a marked decrease in the frequency of the heart's
contraction.^ The causes of this accommodation are unknown.



^ " Snr I'homme et le d^veloppement de ses faculties," Paris, 1835.

^ See Preyer, "Specielle Pliysiologie des Embryo," Leipzig, 1885, S. 179; Eckerlein,
Ztschr.f. Geburtsh. u. Gynak., Stuttgart, 1890, Bd. xix. S. 120.

. ^ Med.-Chir. Trans., London, vol. xxix. p. 137 ; art. "Thorax," Todd's " Cyclopredia of
Anat. and Physiol.," vol. iv. p. 1085.

* Geppert and Zuntz, Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 189.
^ Result of a few observations by Pembrey and Reynolds.



748 CHEMISTR Y OF RESPIRA TION.

Temperature. — The frequency of respiration is greatly increased
when the temperature of the body is raised above the normal by
exposure to excessive heat, or by disease ; this is especially marked in
the dog, for thereby a much greater loss of heat by evaporation of water
from the respiratory tract is effected. Eichet has shown that this rapid
breathing plays an essential part in the regulation of temperature in
the dog.^

The volume of inspiration and expiration — Tidal air. — The
earliest determinations of the volume of an ordinary inspiration in
man appear to have been made by Borellij^ and by Jurin ; ^ the latter
estimated the amount at 656 c.c, or 40 cubic inches. Since that time
numerous determinations have been made with different methods. The
following are some of the results : — 230 cc.,"^ 656 c.c.,^ 574 c.c.,^ ''
492 c.c.,8 278 c.c," 328 c.c.,^o 278 c.c.,11 197 c.c.,i-^ 270 c.c.^^

The causes of these variations are due to differences in the capacity
of the chest of the different subjects of experiment, to individual
differences in the breathing, and to imperfections in the methods
employed. Vierordt^^ has collected the results of the older observers,
and finds as the minimal capacity of a single inspiration 53 c.c.
(Abilgaard), as the maximal 792 c.c. (Senebier). From his own
numerous determinations Vierordt^^ obtained 446 c.c. as the mean
volume of each inspiration, with a frequency of 11 '9 per minute,
whereas Speck ^*^ with a frequency of 6 "3 respirations per minute found
a volume of 1195-1031 c.c. for each inspiration.

Hutchinson 1'' has collected the results of different observers, who
found for the tidal air volumes varying from 49 to 1640 c.c. ; he himself
made eighty determinations on different men, and obtained 114-196 c.c.
during rest, and 262-360 c.c. during exercise ; in one case the tidal air
was as high as 1262 c.c.

Marcet^^ found, as the result of 210 experiments upon two men, a
mean of 250 c.c. for the tidal air, when the rate of respiration was
16 per minute.

The discrepancy in the results given above is natural ; the cases are
not comparable as regards the height, weight, age, sex, and development
of the different subjects of experiment. It is useless, therefore, to
attempt to give any figure which shall represent a true average, and it

^ See "Animal Heat," this Text-book, vol. i. p. 856 ; Mathieii and Urbain, C'om2)t. rend.
Acad. d. sc, Paris, 1872, tome Ixxiv. p. 190.

^ " De Motu Aninialium," p. 2, prop. 81.

^ Phil. Trans., London, 1717-19, vol. xxx. pp. 757, 758.

•* Goodwyn, "Connection of Life with Respiration," London, 1783, p. 28.

^ Menzies, " On Respiration," Edinburgh, 1796, p. 18.

•^ Rieherand, "Physiology," trans, by De Lys, p. 206.

^ Fontana, Phil. Trans., London, 1779, vol. Ixix. p. 349.

* Dalton, 3fem. Lit. and Phil. Soc. Manchester, Ser. 2, vol. ii. p. 26.

^ H. Davy, "Researches," p. 433.

^^ Jurine, " Encyc. Metropol.," art, "Medicine," vol. i. p. 494.
" Kite, "Essays," London, 1795, p. 47.
12 Abernethy, "Essays," 1793, p. 142.
1=* Allen and Pepys, Phil. Trans., London, 1808, p. 256.
"Wagner's " Handworterbuch, " Bd. ii. S. 836.
15 "Physiol, d. Athmens," Karlsruhe, 1845, S. 255.

1" " Untersuch. ueber Sauerstoifverbrauch u. Kohlensiiureausathmung des Menschen,"
Cassel, 1871, S. 31 ; Arch. f. exper. Path. u. Pharmakol., Leipzig, Bd. xii. S. 19.

1'^ Article "Thorax," Todd's " Cyclopa?dia of Anatomy and Physiology," vol. iv.
p. 1067.

1* "Proc. Physiol. Soc," Journ. Physiol., Cambridge and London, 1897, vol. xxi.



VOL UME OF INSPIRA TION AND EXPIRA TION. 749

is much more useful to recognise that the tidal air varies considerably
in different individuals, according to the rate and depth of breathing.

The complemented air is the term given to the extra volume of air
which can be taken into the lungs by the deepest possible inspiration.
Its average value for an adult is said to be 1500 c.c. H. Davy gives
1951 c.c.,^ Kite 3280,2 and Hutchinson 1722-1804 c.c.s

The reserve or stcpplemental air is the volume of air which can be
expelled after an ordinary expiration by a forcible and deep expiration.
This is, according to Bostock's^ determinations, 2624 c.c. (160 cub. in.),
while J. Bell 5 gives 1148 c.c. (70 cub. in.), H. Davy, 1263 c.c. (77 cub.
in.), Hutchinson,^ 1148-1804 c.c. (70-110 cub. in.), and Vierordt, 1226 c.c.

The residual air is the air which remains in the lungs after the
most forcible expiration ; it cannot be driven out of the lungs during
life. The methods "^ employed to determine this volume of air are of
two kinds, those for observations on the dead, and those for observations
upon the Hving body. In the first case, the thorax of the corpse is
forcibly placed in the position of a deep expiration, and then the air in
the lungs is measured. For the determination of the residual air of the
living subject, H. Davy ^ introduced an ingenious method ; he found
by experiment that hydrogen underwent no appreciable change in the
lungs, and that it quickly diffused throughout the residual air; he
therefore respired a quantity of this gas in a gasometer, and then made
a forced expiration, the air of which was analysed. From the quantity
of hydrogen left in the lungs, Davy calculated the total quantity of air
in the thorax at the end of the forced expiration, and found it to be
672 c.c. (41 cub. in.). This method has been used by Grehant,^ and in
a modified form by Hermann '^^ and Berenstein.^^ Several factors have
to be taken into account, such as the absorption of hydrogen by the
blood,^- and its diffusion in the residual air.

Another but less rehable method is Pfliiger's ^'^ pneumonometer. The subject
of the experiment, placed in a special chamber, keeps the chest, as far as
^Dossible, in the position of a forced expiration, the pressure outside the body
is then lowered by a known amount, and the lungs passively give off a certain
quantity of air ; this volume is measured, and from it and the alteration in
pressure the residual air is calculated. The difficulty is to keep the chest in
one position during the experiment.

The results obtained by different observers are given in the follow-
ing table : ^* —

1 "Chem. and Phil. Remarks," p. 410.

^ "Essays and Observations, Physical and Medical," 1795, p. 47.

^ Article "Thorax," Todd's "Cyclopaedia of Anatomy and Physiology," vol. iv. p. 1067.

* "An Elementary System of Physiology," London, 2nd edition, 1828, vol. ii. p. 25.
^ "Anatomy," vol. i. p. 193.

® "Physiologic des Athmens," Karlsrnhe, 1845.

"^ For further details of different methods, see Jacobson, "Beitrage zur Frage nacli dem
Beitr. der Residnalluft, " Diss., Konigsberg, 1887; and Berenstein, "Ein Beitr. z. Bestini-
mung der Ptesidualluft," Diss., Dorpat, 1891.

* "Researches concerning Nitrons Oxide," London, 1800, p. 399.

^ OomjJt. rend. Acad. d. sc, Paris, 1862, tome Iv. p. 279 ; Joiirn. de I'anat. ct physiol.
etc., Paris, 1864, tome i. p. 523.

10 "Lehrbuch der Physiol.," Berlin, 1896, Aufl. 11, S. 126.
" Arch.f. d. ges. Physiol., Bonn, 1891, Bd. 1. S. 363.
12 Zuntz Hermann's "Handbuch," Bd. iv., Th. 2, S. 102.
1^ Arch.f. d. ges. Physiol., Bonn, 1882, Bd. xxix. S. 244.
^■* For some other results, see Hutchinson, loc. cit.



75°



CHEMISTR Y OF RESPIRATION.



Volume of

Residual Air

in O.c.



Method.



1,771 I On corpse.



672-4



1,640

1,230 1

to \

1,640 J

19,800

10,547 1

to \

13,189 J

1,885

400 \

to \

800 J

500

1,231 max. ]

640 mill. -

981 mean J

1,250 max. \

440 min. ;•

796 mean J

526 max. \

347 min. \

478 mean J



On living subject.



On corpse.



On living subject.



On nine corpses.



On living subjects,
sixteen males.



On living subjects,
three females.



Observer.



Goodwyu.^
H. Davy. 2
Allen and Pepys.
Hutcliinson.^
Neupauer.s
Waldenburg.''
Gad. 8
/Pfliiger 9

Kochs.io

f Hermann and
\^ Jacobson.^^



/ Hermann and
\_ Berenstein.12



Hermann and
Berenstein.-'"



Mean of seven experi-
ments.

On one subject ; hydro-
gen method used.



Method defective, re-
sults too high.^

Method defective, re-
sults too high.^



Pneumononieter used.



Hydrogen method used.



Vital capacity is the term given l)y Hutchinson to the vohime
of air which can be expelled from the thorax by the most forcible
expiration, following the deepest possible inspiration. The different
values assigned to this volume of air are shown in the following
table : 13—

1 "Connexion of Life with Respiration," London, 1788, p. 25.

2 "Researches concerning Nitrous Oxide," London, 1800, p. 399.

3 Phil. Trans., London, 1809, pp. 404, 410, 428.

■* Article "Thorax," Todd's "Cyclopaedia of Anatomy and Physiology," vol. iv. p.
1066.

^ BevJ.ichfls Arch. f. Idin. Med., Leipzig, 1879, Bd. xxiii. S. 481.
« Zuntz, Hermann's "Handbuch," Bd. iv. Th. 2, S. 103.
"^ Ztschr.f. klin. Med., Berlin, 1879, Bd. i. S. 27.

* TageU. d. 54 Versamml. deutsch. Naturf. w. Aerzte in Salzburg, ISSl, S. 117.
" Arch.f. d. ges. Physiol., 'Bonn, 1882, Bd. xxix. S. 244.
^"Ztschr.f. kiin. Med., Berlin, 1884. Bd. vii. S. 487.
'^^ Arr.h.f. d. ges. Physiol., Bonn, 1888, Bd. xliii. S. 236, 440.
12 Ihid., 1891, Bd. 1. S. 363.

1^ See also Julius Jeffreys, "Statics of the Human Chest," 1843; Jackson, Am. Med.
Examiner, 1851, p. 51 ; Radclyffe Hall, Trans. Prov. Med. and Sii,rg. Assoc, London,
1851.



VOL UAIE OF INSPIRA TION AND EXPIRA TION. 7 5 1



Vital Capacity.


Observer.


Eemarks.


In Cubic
Centimetres.


In Cubic
Inches.


3608
3608
3493
3058
3280
3280
4920
3558
4838
3558
3700


220

220

213

186-5

200

200

300
217 Mean \
295 Max. J

217

226


Jurin.^

Stephen Hales.-

H. Davy. 3

Thomson."*

Goodwyn.^

Menzies."

Kite.^

Thackrah.8

Hutchinson.^

Hermann and
Berenstein.^°


Mean of twelve
experiments.

Mean for 1923

Men.
Mean for sixteen

Men.



From numerous observations upon men, Hutchinson found that the vital
capacity was influenced by the height, weight, and age of the subjects. The
following table shows the progression of the vital capacity with the stature^^ : —



Height in Feet
and Inches.


Series from

Observations on

1012 Cases.


Series from

Observations on

1923 Cases.


6-6J° '


Cubic In.
175-0

188-5

206-0

222-0

237-5

254-5


Cubic In.
176-0

191-0

207-0

228-0

241-0

258-0


Mean of all
heights


214-0
(3509 c.c.)


217-0
(3558 c.c.)



^ Phil. Trans., London, vol. xxx. p. 757.
- "Statical Essays," 2nd ed., London, 1731, vol. i. p. 243.
2 " Chem. and Phil. Remarks," p. 410.
■* "Chemistry of Animal Bodies," 1843, p. 610.
^ " Connexion of Life with Respiration," London, 1788.
^ " On Respiration," Edinburgh, 1796.

■^ " Essays and Observations, Physical and Medical," 1795, p. 48.
8 "On the Effects of Arts, Trades, etc., upon Health," London, 1831, p. 21.
« Loc. cit. 1° Arch./, d. ges. Physiol., Bonn, 1891, Bd. 1. S. 363.

" 1 Foot = 304-8 mm.; 1 inch = 25-4 mm. ; 1 cubic inch = 16-4 c.c.



752



CHEMISTR Y OF RESPIRA TION.



There is an irregular increase of the vital capacity
regards age there is an increase




Fig. 68. — Hutchinson's spirometer.



with weight, and as
from 15 to 35 years, 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 complemental, 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 ^ 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 fvill 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. ^ 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.-^

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.-^ 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 "Lelirbuch der Physiol.," Berlin, 1896, Aiifl. 11, S. 126.

^Eckerlein, Ztsclir. f. Geburtsh. u. Gyndk., Stuttgart, 1890, Bd. xix. S. 120.

^ Hermann, loc. cit., S. 127.

4 For further details, see Hutchinson, article "Thorax," Todd's " Cyclopeedia of
Anatomy and Physiology," vol. iv. p. 1069.

■' Fleischl von Marxow, Ccntralbl. f. Physiol., Leipzig u. Wien, 1888, S. 39 ; Clar,
Wien. klin. JFchnschr., 1889, No. 18 ; Marcet, " Proc. Physiol. Soc." Journ. Physiol., Cam-
bridge and London, 1897, voL xxi. ; Hanriot and Richet, ConijJt. rend. Soc. de biol., Paris,
1887, p. 405.



RATE OF RESPIRATION IN DIFFERENT ANIMALS. 753





Cubic
Centimetres.


Cubic
Inches.


Complemental air .

Tidal air

Resei've or supplemental air .
Eesidual air


1700] Vital

300 \ capacity,
1500j 3500.
1000


104] Vital
18 V capacity,
91 J 213.
61



Hyperpncea, dyspiKza, asphyxia, apncea, and Clicyne- Stokes' respira-
tion. — These different conditions are considered elsewhere in this work.^

The rate of respiration in different animals. — ^Numerous observa-
tions upon the rapidity of tlie respiratory movements in different animals were
made by Paul Bert,'^ and the following table gives results obtained cliiefly by
him : —





Number of






Animal.


Respirations
per Minute.


Remarl£S.


Observer.


Mammals — ■








Monkey ....


19


Quiet.


Paul Bert.


Tiger .






6


J,




Lion






10


,,




Cat . . .






24


,,


J ,


Dog .






15


,,




Ox . . .






30


J,


Robertson. ^


Rabbit .






55


,,


Paul Bert.


Rat, black and white






210


^j




Rhinoceros .






6


Drowsy.


11


Horse .






10-12


Quiet.


,,


BlEDS —








Condor ....


6


jj


^,


Pelican






4


) J


jj


Cock .






12


Lying down.


,,


Dove .






30


Quiet.


jj


House-sparrow






90


,,




Canary






100


>>





Reptiles—








Rattle-snake.


5






Lizard


12




,,


Fishes —








Skate [PMia hatis) .


51


)>


Lafont.'*


Dogfish






40


53


J J


Perch .






30




Paul Bert.


Sole






34


, J


Lafont.


Conger-eel .






10


Quiet ; length of


Paul Bert.






animal, 1 metre.




)> ....


25


Quiet; length of
animal, 50 cm.


))


Ceustaceans —








King-crab {Liviiohis)


12


Moving.


J)


Molluscs —








Poulp


28


Quiet.


,,


Cuttlefish ....


45


) )


Lafont.


Squid


65




Paul Bert.



^ This article, pp. 743, 765 ; also "Mechanism of Respiration," this Text-book, vol. ii,
^ "Lecons sur la physiol. comp. de la respiration," Paris, 1870, p. 393.
^ Veterinary Journal, London, 1885, vol. xx. p. 311. The rate of respiration in 250
animals varied from 11 to 106 per minute.
■^ Qiroted by Paul Bert, loc. cit.
VOL. I. — 48



754 CHEMISTR Y OF RESPIRA TION.

The general conclusion to Le drawn from these and other similar data is
that the larger animals respire more slowly than the smaller animals of a
similar class. It has heen shown that a similar difference obtains in the out-
jjut of carbon dioxide and the intake of oxygen.

The alveolar surface of the human lungs. — The volume of the lungs
in the mean phase of respiration is about 3500 c.c; the diameter of a single
alveolus is about 0'2 mm., its volume '004 c.mm., and its surface 0'126 s.mm.
In order to contain the air in the lungs, there must be 725 millions of alveoli,
with a surface of about 90 sq. metres. ^ The above calculation is the one given
by Zuntz.2

The changes in the composition of the air during respiration. —

The fresh air taken into the kings during respiration has the folio mng
composition, when it is dry and measured at 0° and 760 mm. pressure,
20-96 volumes per cent, oxygen, 79'02 nitrogen,^ and about 0"03 carbon
dioxide, or by weight per cent., 23'015 oxygen, and 76'985 nitrogen.
Under ordinary conditions, the air contains a quantity of aqueous
vapour, which is liable to considerable variations according to the
temperature and other atmospheric conditions ; the carbon dioxide,
moreover, may in badly-ventilated rooms rise considerably above the
amount just given.

The inspked air is warmed and moistened in passing through the
nose, pharynx, trachea, and bronchi, and rapidly mixes and diffuses with
the air retained in the alveoli of the lungs. The passage of the air
through the nose alone raises the temperature of the air considerably ;
thus Bloch * found that, when the temperature of the external air was
-8°, -0°'5 to 3°"5, 12° to 16° and 18°, that of the au' entering the pharynx
from the nose was respectively 24°-5, 26°, 30°, and 31°. With a
moderate external temperature the air becomes about one-third saturated
with moisture during its passage through the nasal cavity. The rapidity
of the processes of mixture and diffusion will vary according to the
frequency and depth of breathing and the capacity of the lungs. The
air exphed will Hkewise vary in composition, and under normal condi-
tions will never represent the alveolar air.

Tlu expired air. — The earliest determinations of the composition of
the expired air of man were made by Menzies,^ Lavoisier and Seguin,*^
H. Davy,'^ Allen and Pepys,^ and Prout.^ The followmg table gives the
more exact results of recent investigations, but at the same time it is
important to remember that it is impossible to give figures which shall
exactly represent the average composition of the expired air; the
percentage of oxygen and of carbon dioxide varies according to the
frequency and depth of breathing, and is influenced by various condi-
tions which affect the metabolism of the body, such as muscular
activity, temperature, and food. For these reasons the respiratory ex-
change of an animal should be estimated by the direct determination
of the intake of oxygen and the output of carbon dioxide and water in

1 1 mm. = 0-03937 in., aud 1 metre = 39-37079 in.

2 Arch. f. d. ges. Physiol., Bonn, 1888, Bd. xlii. S. 410.

^ This includes a small quantity of argon, but it ap[)ears to have no physiological
importance.

* Ztschr.f. Ohrcnh., "Wiesbaden, Bd. xviii. S. 215, 354.

■'' "Essay on Respiration," EiJiuburgh, 1796, p. 50.

® Ann. de chim., Paris, 1814, tome xci. p. 318.

"^ "Researches," London, 1808, p. 331.

^ Phil. Trans., London, 1808, 1809.

9 Ann. Phil., London, 1813, vol. ii. p. 328.



COMPOSITION OF THE AIR DURING RESPIRATION. 755



a given time, not ]:)y a calculation based upon the alteration in the com-
position of the air of several expirations, multiplied by the average
quantity of expired air and the average number of respirations in a
given time.



Breathing.


Volume of
Expired
Air (per
Minute).


Percentage

of Oxj'gen

in Expired

Air.


Quantity
of Oxygen
Absorbed

(per
Minute).


Percent-
age of
Carbon
Dioxide in
Expired
Air.


Quantity
of Carbon
Dioxide Dis-
charged (per
Minute).


Observer.


Normal
Ver}' shallow
Very deep .
Normal. Best
Work

Hard work .
Normal
Normal




c.c.

7, 527

5,833

17,647

6,158

16,191

24,323

4,644

3,419


16-29
15-50
18-29
17-00
17-29
16-96
16-16
16-96


C.C.

358
330

437

240

587

964

222-9

136-8


4-21
4-63
3-17
3-56
3-65
4-08
4-36
3-44


C.C.

318

269

560

218

593

993

202-7

117-6


I Speck. 1

tspeck.2
^Lowy.^



Vierordf^ concluded from his experiments that the percentage of
carbon dioxide in the expired air diminished, but the total discharge
increased vs^hen the respiration was voluntarily quickened, the depth of
breathing remaining the same, 500 c.c. ; similar effects were produced by
breathing more deeply but with the same frequency. The drawback to
these observations is that they were for periods only lasting two or
three minutes, and thus they are no exact measure of changes of meta-
bolism. Even the extended observations of Lossen and Berg have been



Online LibraryE. A. (Edward Albert) Sharpey-SchäferText-book of physiology; (Volume v.1) → online text (page 105 of 147)