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the intake of oxygen
and output of carbon dioxide checks the result of the calorimetric observa-
tion.

1 Rosenthal, Arch. f. Pliysiol., Leipzig, 1878, S. 349 ; Richet, Arch, de physiol. norm,
et path., Paris, 1885, tome vi. p. 237 ; Mosso, Arch. f. cxper. Path. it. Pharmakol., Leipzig,
1890, Bd. xxvi. S. 316.

- Journ. de Vanat. et 'physiol. etc., Paris, 18S6, tome xxii.

^ Arch.f. Physiol., Leipzig, 1888, S. 1.

■* " Calorimetrische Methodik," Marbm-g, 1891; Beitr. z. Physiol. Carl Ludwig
z. s. 70 Geburtst., Leipzig, 1887 ; Ztschr. f. Biol., Miinchen, 1893-94, Bd. xxx.
S. 92.

^ Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 123; Hale White,
Croonian Lectures, Lancet, London, 1897, vol. ii. ; and Brit. Med. Journ., London, 1897,
vol. ii. p. 11.




Fig. 83.



-Diagram of air calorimeter (Haldane, Hale
White, and Washbourn).



F. Layer of felt.
C. Cage.



M.



I A. Tubes for ventilation.

I H. Hydrogen flame.

Manometer.



846 ANIMAL HEAT.

For experiments on man, Currie,^ and afterwards Liebermeister - and others,
used a bath as a water calorimeter ; this method is liable to many sources of
error. Scharling,^ Vogel,'* and Hirn ^ used a method which was simple, but at
the same time untrustworthy ; the subject of the experiment was enclosed
within a small chamber standing in a room with a constant temperature ; the
production of heat was determined from the difference between the tempera-
ture of the chamber and that of the room. Leyden employed a partial
calorimeter for experiments in man ; a limb was enclosed in a suitable water
calorimeter.

It is probable that the simplest and most useful method for clinical
purposes is that introduced by Waller ^'■, the deep and surface temperatures
of different parts of the body are determined, the evaporation of water from
the skin is estimated by a hygrometer, and the temperature of the surrounding
air is noted. If the calorimetric value of the thermometer scale be pre-
viously determined on a surface giving off heat at a known rate, it is possible
from the data obtained to calculate the emission of heat. The apparatus, in
fact, constitutes a heat manometer measuring the temperature difference
between the skin and atmosphere.

The results of • calorimetric experiments.— Lavoisier '^ and Craw-
ford ^ concluded from their results that the heat produced by an animal
could be almost entirely accounted for by the combustion represented
by the discharge of carbon dioxide and water. Dulong ^ and Despretz's ^°
data, when corrected by Liebig,^'' Helmholtz,i2 Gavarret,^" Ludwigj^"^ Milne
Edwards,^^ and Liebermeister ,1^ lead to a similar conclusion, but since the
more exact experiments of Eubner and others, they have had only a
historical interest.^'''

The table on p. 847 gives some of the more important results
obtained by various observers.

It has been already shown that the heat, measured directly with a
calorimeter, is equal to that calculated from the heats of combustion of
the constituents of the food (Eubner ^^), and it will be seen later that the
production of heat in different warm-blooded animals is proportionate to
the surface of their bodies (Rubner).^^ During digestion and muscular
work the production of heat is greatly increased.

According to Langlois,^*' the production of heat in children is pro-
portionate to the surface of their skin, and shows a daily variation.

1 " Medical Reports on the Effect of Water, Cold and Warm, as a Eemedy in Fever and
other Diseases," Liverpool. 1798.

2 Arch./. Anat., Physiol, u. wissensch. Med., 1860, S. 520, 589 ; 1861, S. 28 ; " Hand-
bnch der Path. u. Therap. des FielDers," 1875, S. 142.

" Journ. f. prald. Chem., Leipzig, 1849, Bd. xlviii. S. 435.

"* Arch. d. Ver. f. wissensch. Heilh., Leipzig, 1864, S. 442.

•' " Recherches sur I'^quivalent mecaniqne de la chaleur," Paris, 1858.

^ " Proc. PhysioL Soc," Journ. Physiol., Cambridge and London, 1894, vol. xv.

^ Hist. Acad. roy. d. sc, Paris, 1780, p. 355.

* " Experiments and Observations on Animal Heat," 1788, 2ud edition.

3 Ann. d. chim. ct2Jhys., Paris, 1843, Ser. 3, tome i. p. 440.

10 lUd., 1824, Ser. 2, tome xxvi. p. 337.

11 "Thierchemie.".S. 28.

12 "Encyclop. Worterb. d. med. Wissensch.," 1846, Bd. xxxv. S. 523.

13 " De la chalenr produite paries etres vivants," 1855, p. 219.
» "Lehrbuch d. Physiol.," 1861, Aufl. 2, Bd. ii. S. 739.

1-'' " Lemons sur la physiologic," 1863, tome viii. p. 23.
16 "Handbuch der Path. u. Therap. des Fiebers," 1875, S. 134.

1'^ For a discussion of these results see Rosenthal, Hermann's "Handbuch," Bd. iv. Th. 2,
S. 358.

18 Ztschr. f. Biol., Munchen, 1894, Bd. xxx. S. 135. This article, pp. 833-37.

19 Ztschr.' f. Biol., Miinchen, 1883, Bd. xix. S. 535. This article, p. 853.

20 Ceniralbl.f. Physiol., Leipzig u. Wien, 1887, S. 237.



ME A S URE OF HE A T FR OD UCTION.



847



Heat Produced.



Remarks.



Observer.



132,000 cal. per hour.
140,000 ,,
99,000 ,,

21,000 cal. per hour.

12,630 ,,

10,900 ,,



2, 500 cal. per hour and
per kilo.



5,920 cal. per hour and

per kilo.
6,000 „ ,,



Adult man.



Dog weighing
6350— 5450 grms.



Dogs.



Pigeon.



At rest.

Partial calorimeter

used.
One hour after food.

Twenty-six hours

after food.
About forty-nine

hours after food.

About thirty-six
hours after food.

Mean of experiments
on six dogs.

Normal.

After removal of
cerebral hemi-
spheres.



Scharling. ^
Hirn.-

Leyden.'"

Senator.''



Corin and Van
Beneden."



The respiratory exchange as a measure of heat production. —

The heat of the body has been shown to be due to processes of com-
bustion occurring in the tissues. The respiratory exchange is a measure
of this combustion, and hence a determination of the intake of oxygen
and the output of carbon dioxide is a measure, although not a perfectly
accurate one, of the heat produced. There is, however, one source of
inaccuracy in this method ; a determination of the respiratory exchange
during a limited time is not an exact indication of the combustion occur-
ring during that time, for we know that oxygen may be taken up and
stored in the body for a considerable period, and carbon dioxide may be
given off by the breaking up of previous combinations ; in fact, may still
be evolved when the tissues are receiving no free oxygen. Nevertheless,
consecutive determinations of the respiratory exchange for long periods,
and careful observations of the animal's temperature, form a most valu-
able method for the study of the regulation of temperature by heat
production, especially since calorimetric experiments are more tedious,
difficult, and more open to accidental sources of error.

In the case of warm-blooded animals, a fall in external tempera-
ture increases, a rise diminishes the intake of oxygen and the out-
put of carbon dioxide. Crawford ^ and Lavoisier "^ came to this
conclusion not only on theoretical grounds, because they believed that
animal heat was due to combustion, but from the results of direct
experiment.

"^ Joiim. f. lyrcM. Cliem., Leipzig, 1849, Bd. xlviii. S. 435.

" " Recherches sur I'equivalent mecanique de la chaleur," Paris, 1858 ; "Exposition
analytique et exp^rimentale de la th^orie mdcanique de la chaleur," Paris, 1875, 3e edition,
tome i. p. 27.

^ Deutsches Arch. f. klin. Med., Leipzig, 1869, Bd. v. S. 273.

* Centralbl.f. d. med. Wissensch., Berlin, 1871 ; Arch. f. Anat., Physiol, u. wissensch.
Med., 1872, S. i. ; 1874, S. 18; " Untersuch. ueber den fieberhaften Process und seine
Behandlung," Berlin, 1873, S. 30.

® Arch, de hiol., Gand, 1887, tome vii. p. 276.

^ " Experiments and Observations on Animal Heat," 1788, 2nd edition.

■^ Hist. Acad. roy. d. sc, Paris, 1780, p. 407.



ANIMAL HEAT.



Numerous observations have been made, chiefly by Pfliiger and his
pupils, upon the effect of changes in external temperature upon the
respiratory exchange of animals in normal and abnormal conditions.
The results of some of the most important experiments will now be
given •} —



Tempera-
ture of Air.



4°. 4

6° -5
9°-0
14° -3
23°-7
26°-7
30'-0

7°-3

16°-9

3°-64
26° -21

-5° -5
2°-0
12°-3
20°-l
29°-6

-9°-0

l7°-5



Intake of Oxygen.



Output of Carbon
Dioxide.



1496-66 c.c. per hour
and kilo.
1086-8

1856-8
1118-5

17-48 grms. in 6 hours

15-79

17-71

12-78

13-91



210-7 grms. in 6
hours.
206-0
192-0
155-1
164-8
160-0
170-6

1203-44 c.c.

937-01 ,,

1564-8 ,,
1057-4 ,,

19-83 ,,

17-87 ,,

17-63 ,,

14-34 ,,

13-12 ,,

3016 c.c. per hour
and kilo.
1141



CO2

0„



0-80
0-86



0-83
0-94



Animal.



Observer.



Man

weighing
71 kilos.



Guinea-
pig-

Guinea-
pig-
Cat

weighing
about 2-5
kilos.

Pigeon.



Voit.



Colasanti.*



Tinkler.



Herzog
Carl
Theodor.^



Corin and
Van Bene
den.''



It will be seen from the above table that the respiratory exchange
decreases with a rise in external temperature, until a point about 35°
is reached, when an increase in the metabolism occurs.'' The response
to a change in temperature is, in the case of small mammals, almost
immediate.^ Thus, within two minutes of a change from 30° to 18^
a mouse increased its output of carbon dioxide by 74 per cent. ; within
one minute of a change from 33°-25 to 17° '5 the increase was 60 per
cent. The response to an increase in temperature does not take place
so quickly ; thus, within two minutes of a rise from 18° to 34° -5,
the decrease in the output of carbon dioxide was 18 per cent. ;
within one minute of a rise from 17° to 32°, the decrease was 5
per cent. The power of maintaining a constant mean temperature is
readily tested in this manner, as the following example will show
(Pembrey) : —

1 See also the preceding article on " Chemistry of Respiration."

^ Ztschr.f. Biol., Miinchen, 1878, Bd. xiv. S. 57.

'■^Arch.f. d. ges Physiol., Bonn, 1877, Bd. xiv. S. 92.

"^ Ihid., 1877, Bd. xv. S. 603.

5 Ztschr.f. Biol., Munchen, 1878, Bd. xiv. S. 51.

^ Arch de bioL, Gand, 1887, tome vii. p. 274.

■'See also Page, Journ. Physiol., Cambridge and London, vol. ii. p. 228; and
"Chemistry of P>,espiration," this Text-book, vol. i. p. 712.

8 Pemljrey, Journ. Physiol., Cambridge and London, 1894, vol. xv. p. 401. See also
"Chemistry of Respiration," this Text-book, vol. i.



PRODUCTION OF HEAT IN COLD-BLOODED ANIMALS. 849
Consecutive Periods of Thirty Minutes.



COain
Decimilligrammes.


External
TemiDerature.


Remarks.


1055
957
518
262
815
683


ll°-0

ii°-o

31°-5
32°-5
ll°-0
ll°-0


Mouse shivering and active, face and ears pale.

Mouse less active, ears pale.

Mouse quiet, sweating, ears flushed.

Mouse sprawled out, sweating, apparently asleep.

Mouse wakes up, Lecomes very active, ears pale.

Mouse quiet, ears pale.



The Production of Heat in Oold-Blooded Animals.

One of the most characteristic phenomena of life is an exchange of material,
an oxidation which results in the production of heat. In the lowest forms of
life, both vegetable and aniznal, a certain amount of heat is produced.
JSTumerous experiments have shown that this is so, although, owing to the
cooling effect of evaporation from the surface of the body, the heat produced
may be masked by the excessive loss ; the temperature of a frog may be
lower than that of the air, notwithstanding that the animal is constantly
producing heat.

It is unnecessary to give here an account of the temperature of plants,^
but, in addition to the facts already stated,^ further details must be brought
forward concerning the production of heat in the lower animals. Hunter ^
found that the temperature of earth-worms, slugs, and leeches might be a degree
above that of their surroundings ; a carp had a temperature of 20° "6, a viper
one of 20°, when that of the surroundings was 18° "6 and 14°"4 respectively.

In bees, even in winter, the capacity for producing heat has already been
shown to be very great. ISText in point of interest is the fact, to which
attention was first drawn by Valenciennes,* that pythons, when coiled
round their eggs during incubation, maintain a temperature even 20°
above that of the surrounding air. The following are some of the results
obtained by Sclater,^ who compared the temperature of a female python with
that of the non-incubating male, which was kept in the same compartment of
the reptile house : —



Dates.


Temperature of
Air in Den.


Temperature of Male.


Temperature
of Female.


Feb. 12
March 2


14° -8 \
15°-6 J


On surface, 21° "2
Between folds, 23° -8
On surface, 22^*0
Between folds, 2 4° '4


22°-8
27°-5
28°-9
35°-6



^ See on this subject Dutrochet, Ann. cl. sc. nat., Paris (Botanique) 1840, S6v. 2, tome
xiii. pp. 5 and 65 ; Gavarret, " De la chaleur produite par les etres vivants," Paris, 1855,
p. 516; Sachs, "Physiology of Plants," p. 404; Vines, " Physiology of Plants " ; Van
Tieghem, "Traits de botanique," Paris, 1891, tome i. It is interesting to notice that an
abnormal rise of tempei-ature, fever in fact, has been observed in the tissues around a
wound in a plant. — Annals of Botany, 1897.

- This article, p. 792.

^ " Works," Palmer's editiou, London, 1837, vol. iv. p. 131 et seq.

'' Compt. rend. Acad. d. sc, Paris, 1841, tome xiii. p. 126.

^ Froc. Zool. Sac. London, 1862, p. 365.
VOL. I.— 54



8so



ANIMAL HEAT.



Forbes ^ made similar observations, and found, as the average temperatures
between the folds of the body, 30° and 31°-7 in the case of the male and
female respectively; the maximum was 32°*1 for the male, and 33° '8 for
the female. The greatest difference between the temperature of the air and
the surface of the snake was 4°'6 in the male, and 5°*3 in the female ; between
the air and the coils of the snake, 6°'4 in the male, and 9°"3 in the female. It
is worthy of note that the female took no food and little exercise for many
weeks before and during incubation.

In some fishes a temperature several degrees above that of the water has
been observed. Thus Davy ^ found the temperature of deep-seated muscles of
the bonito {Thynnus pelamys) to be 37°'2, when that of the sea M'as 26°"9.
The tunny (Thynnus thynnus) is said to have a similar high temperature.

The embryo of the chick must be looked upon as a cold-blooded animal,
for it responds to changes of temperature in a similar manner," yet even at an
early stage the production of heat within its tissues can be shown to be
considerable. Thus Barensprung * found that the temperature of an egg on
the fourth day of incubation was '6 above that of a dead egg and 'S above
that of the incubator.

The Regulation of Loss of Heat.

An animal may lose heat in various ways — by direct conduction and
radiation from the skin, by evaporation of sv^eat, by the warming of air
during respiration and by evaporation from the different parts of the
respiratory system, by raising cold food and drink to the temperature
of its body, and by the discharge of urine and fseces. Loss of heat is
controlled chiefly by the skin and the lungs.

The distribution of the loss of heat by an adult man in twenty-four
hours has been estimated by various observers as follows : —



Vierordt.



1-8% by urine and faeces .. =

3 '5% by expired air . . . . =
7 '2% by evaporation from lungs =
14'5% ,, ,, „ skin =

73"0%by radiation and conduction
from skin



47,500 calories,

84,500
182,120
364,120

1,791,820



2,500,000



Helmholtz.



= 2-6 %■
2-6%
= 14-7% 1^2,732,000
calories,
•=80-1%



Ludwig.



2-l-%
7-2%



78-5%



^2,706,076
^ calories.



Loss of heat by the skin— Radiation and conduction. — The
amount of heat lost by radiation and conduction is, within certain
limits, in proportion to the difference in the temperature of the body
and of its surroundings ; the warmer the skin and the colder the
surroundings, the greater will be the loss of heat. The heat of the skin
is controlled by the cutaneous circulation, and this in turn is regulated
by the central nervous system. The general result is that the cutaneous
blood vessels are contracted, the circulation is smaller, and the skin
pale and cold, when the external temperature is low ; on the other
hand, the vessels dilate, the circulation becomes greater and the skin
red and warm, when the temperature of the surroundings is high.



1 Proc. Zool. Soc. London, 1881, p. 960.
^ "Researches," London, 1839, vol. i. p. 219.

^ Pembrey, Gordon, and Warren, Journ. Physiol., Cambridge and London, 1894-95,
voL xvii. p. 331.

'^ Arch. f. Anat., Physiol, u. wisscnsch. Med., 1851, S. 131.



RE G JjLA TION BY E VAPOR A TION. 8 5 1

Thus it happens that the animal can diminish or increase its loss of heat
according to its needs.

Other conditions, however, play an important part in this regula-
tion. In the case of man the epidermis and the subcutaneous fat are
bad conductors ; and, by means of clothing,^ the greater part of the body
is so protected that it is in contact not with the external air, but with
a fairly stationary layer of aii-, with a temperature from 24° to 30°. In
other warm-blooded animals protection is afforded by the fur or feathers,
which prevent loss of heat not only by their thickness and slight power
of conduction, but by enclosing strata of more or less stationary warm
air. The more stationary the air the less the loss of heat, for the body
becomes surrounded with a layer of air having a temperature inter-
mediate between that of the body and of the atmosphere. Thus, during
Parry's expedition to the Polar seas, the sailors found that they could
better bear a cold which would freeze mercury ( — 40°), when the air
was perfectly calm, than a temperature of — 12°*2 when there was a
wind.^ The men of Franklin's expedition had the same experience.^
Further, the capacity of dry air to take up heat is much less than that
of moist air ; hence it happens that in dry, calm air several degrees below
zero, much less sensation of cold may be felt than in moist air with a
temperature a few degrees above the freezing point.

In the whale, seal, and walrus, the thick epidermis and the large
amount of subcutaneous fat so perfectly prevent excessive loss of heat,
that their high temperature can be maintained in the Arctic seas.
Greyhounds, on the other hand, feel even moderately cold weather very
quickly, for, as the result of selective breeding, they have little fur and
hardly any subcutaneous fat.^ Vierordt ^ calculated that an adult man
lost 1,791,820 calories, or 73 per cent, of the total loss of heat, by
radiation and conduction from the skin in twenty-four hours. Masje,^
from experiments made with a thermoscope, constructed on the principle
of Langley's bolometer, concludes that the heat lost by radiation from
the skin of an adult man, weighing 82 kilos, and with a surface of
20,000 square cms., is 1,700,000 calories in twenty-four hours. Similar
experiments have also been made by Stewart.'^

Evaporation.— Benjamin Franklin ^ observed, during the hot weather
at Philadelphia in 1750, that his temperature remained normal, although
the external temperature was 37°'8 in the shade. He attributed this
result to the cooling effect of the evaporation of sweat. This was proved
by Blagden ^ during his experiments upon the effect of extreme heat on
the body. When the air was moist, the temperature of the body rose ;
whereas in djry air, heated to 126°, the temperature did not rise above
the normal. Into the heated room two jars of water were brought, and
a layer of oil was placed on the surface of the water in one, with the

1 Schuster, Arch. f. Hyg., Muncheii u. Leipzig, 1888, Bd. viii. S. 1; Rubner, ibid.,
1890, Bd. xi. S. 255.

- "Journal of a Second Voyage to the Arctic Regions."

'^ Franklin, " Journey to the Polar Sea, 1819-1822," 2nd edition, vol. ii. pp. 27, 28. See
also Ross, " Narrative of a Second Voyage in Search of a North-West Passage," London,
1835, pp. 285, 287, 297.

4 Bergmann, " Gottinger Studien," 1847, Abth. 1, S. 595.

^ "Grundriss der Physiol, des Menschen."

s Virchow's ArcJiiv, 1887, Bd. cvii. S. 17, 267.

■^ SHid. Physiol. Lab. Owens Coll., Manchester, 1891, vol. i. p. 100.

* "Experiments and Observations on Electricity," London, 1769, p. 366.

^ Blagden, Phil. Trans., London, 1775, vol. Ixv. pp. Ill and 484.



852



ANIMAL HEAT.



result that it quickly boiled, owing to the alDseuce of evaporation ;
whereas the water in the other jar rose to 60°, but did not boil, evapora-
tion taking place freely from the surface and thus cooling the water.
Upon the loss of heat by evaporation Crawford,^ in 1781, made some
interesting experiments upon frogs ; he compared the rates of warming
of a dead and a living frog by exposure to warm air and to warm w^ater,
and found that the temperature of the former rose more rapidly than
that of the latter.

In another experiment he found that, when the air was 25°, the skin of a
living frog was 20°, the stomach 21°-4; when the water was 16°'l, the skin of
a living frog was 16°"2, the stomach 19° •2, It is to he noted that when the
frog was kept in water its nose was above the surface, so that it might breathe ;
in this way heat might be lost by evaporation from the lungs. Crawford,
however, concluded from his experiments that the cooHng was not solely due
to evaporation, and that animals had the power of "producing cold."

In 1810, Delaroche - pubKshed some instructive experiments, similar to
those of Blagden, to show the effect of evaporation. He placed an alcarraza ^
full of water at 35°, and a rabbit whose temperature was 39° "7, in a stove
heated to 45° ; the temperature of the rabbit gradually rose to 43° "8, while
that of the alcarraza fell to 31°"4, and remained stationary. In the second
experiment he placed a frog and two pieces of moist sponge in a stove heated
to 36°'5, and found at the end of an hour that the frog's temperature was
stationary at 28°'2, and that of the pieces of sponge at 27°"9 and 27°'6.
Delaroche contests the results of Crawford's experiments on frogs, and main-
tains that these animals quickly take the temperature of the water in which
they are placed, and that in this respect there is no difference between a dead
and a living frog.

According to the calculations of Vierordt and Ludwig, from 10 to 20
per cent, of the total daily loss of heat in an adult man is due to
evaporation from the skin and respiratory tract. Further details on the
discharge of water from the skin and lungs are given in another part of
this work.^ The following values for the discharge of moisture from
various parts of the human skin were observed by Waller : ^ —



External
\ tempera-
ture, 20°.



The influence of the size of the body upon the regulation of tem-
perature.— The importance of the relation between the surface of the
body and its mass, in respect to the loss and production of heat, was first

The bio-o-er an animal the greater the ratio of



Palm of hand


24 mgrms. pt


Sole of foot


14


Forehead


12


Cheek .


6


Axilla .


10


Popliteal space


10


Porearm .


5


Leg


5



pointed out by Bergmann.

1 Crawford, Phil. Trans., London, 1781, vol. Ixxi. p. 485.

- Delaroche, Journ. dephys., Paris, 1810, tome Ixxi. pp. 294-296.

" A porous jar used for keeping water cool in hot climates. See also Edwards, "De
I'influence des agens physiques sur la vie," p. 84.

^ "Chemistry of Respiration," this Text-book, vol. i. p. 711.

^ " Proc. Physiol. Snc.," Journ. Physiol., Cambridge and London, 1894, vol. xv. For
further observations see Hale White, C'roonian Lectures, Lancet, London, 1897, June 19
and 26, and Brit. Med. Journ., London, 1897, vol. i. p. 1654 et seq.

« "Gottinger Studien," 1847, Abth. 1, S. 595.



REGULATION OF TEMPERATURE.



853



its volume or weight to its surface, for weight or volume increases as the
cube, surface increases as the square. Thus, if the dimensions of a body
be increased from 1 to 2, the surface increases from 1 to 4, and the cubic
content from 1 to 8. A small animal, therefore, has a far greater
surface in relation to its weight than a large animal, and if it is to
maintain its temperature at a similar height, it must have either special
means for preventing an excessive loss of heat or a more rapid produc-
tion of heat. Both of these means are employed, and so effective are
they, that the temperature of the smallest mammals and birds is often
higher than that of the biggest. A mouse has a thicker covering



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