reaction ; they, in fact, behave like inert foreign matter.
246. Increase in Size and Weight during Growth,
The length of the body, which at birth is usually ^ of the adult body, undergoes
the greatest elongation at an early period : in the first year, 20; in the second, 10;
in the third, about 7 centimetres; whilst from 5-16 years the annual increase is
about 5| centimetres. In the twentieth year the increase is very slight. From
50 onwards the size of the body diminishes, owing to the intervertebral discs
becoming thinner, and the loss may be 6-7 centimetres about the eightieth year.
The weight of the body (^ of an adult) sinks during the first 5-7 days, owing to
the evacuation of the meconium and the small amount of food which is taken at
The increase of weight is greater in the same time than the increase in length.
Within the first year a child trebles its weight. The greatest weight is usually
INCREASE IN SIZE AND WEIGHT.
reached about 40, while towards 60 a decrease begins, which at 80 may amount
even to 6 kilo. The results of measurements, chiefly by Quetelet, are given in the
(Chiefly from Quetelet).
Between the 12th and 15th years, the weight and size of the female are greater
than of the male. Growth is most active in the last months of foetal life, and
afterwards from the 6th to 9th year, until the 13th to 16th. The full stature is
reached about 30, but not the greatest weight (Thoma).
General View of the Chemical Constituents
of the Organism,
247. (A.) Inorganic Constituents.
I. Water forms 58-5 per cent, of the whole body, but it occurs in different
quantity in the different tissues; the kidneys contain the most water, 827 per
cent.; bones, 22 per cent.; teeth, 10 per cent.; while enamel contains the least,
0'2 per cent.
[ Water is of the utmost importance in the economy, and it is no paradox to say
that all organisms live in water, for though the entire animal may not live in
water, all its tissues are bathed by watery fluids, and the essential vital processes
occur in water (p. 458). A constant stream of water may be said to be passing
through organisms, a certain quantity of water is taken in with the food and
drink, which ultimately reaches the blood, while from the blood a constant loss is
taking place by the urine, the sweat and breath. The greater quantity of the water
in our bodies is derived from without, but it is probable that a small amount is
formed within our bodies by the action of free oxygen on certain organic sub-
stances. According to some observers, peroxide of hydrogen (HgOg) is also
present in the body.]
II. Gases. [Oxygen is absorbed from the air, and enters the blood, where it
forms a loose chemical compound, with the colouring matter or haemoglobin, while
a small amount exists in a free state, or is simply absorbed.] Hydrogen is found
in the alimentary canal. Nitrogen [like oxygen, is absorbed from the atmosphere
by the blood, in which it is dissolved, and from which it passes into other fluids
of the body. It is probable that a very small quantity is formed within the body.]
The presence of Marsh gas (CH 4 ) (p. 255), ammonia (NH 3 ), and sulphuretted
hydrogen (H 2 S) (p. 372) has been referred to already.
III. Salts. Sodium chloride [is one of the most important inorganic
substances present in the body. It occurs in all the tissues and fluids
of the body, and it plays a most prominent part in connection with
the diffusion of fluids through membranes, and its presence is necessary
for the solution of the globulins (p. 502). In some cases it exists in
a state of combination with albuminous bodies, as in the blood-plasma.
Common salt is absolutely necessary for one's existence; if it be
withdrawn entirely, life soon comes to an end. About 15 grammes
are given off in twenty-four hours, the great part being excreted by
the urine. Boussingault showed that, the addition of a certain
amount of common salt to the daily food of cattle greatly improved
Calcium phosphate [ (Ca 3 P 2 8 ) is the most abundant salt in the body, as it forms
more than one-half of our bones, but it also occurs in dentine, enamel, and to a
500 SALTS, ACIDS, AND BASES IN THE BODY.
much less extent in the other solids and fluids of the body. Amongst secretions,
milk contains relatively the largest amount (2 '72) per cent. In milk it is neces-
sary for forming the calcareous matter of the bones of the infant. It gives bones
their hardness, solidity, and rigidity. It is chiefly derived from the food, and as
only a small quantity is given off in the excretions, it seems not to undergo rapid
removal from the body.]
Sodium phosphate (PNa 3 4 ), acid sodium phosphate (PNa 2 H0 4 ), acid
potassium phosphate (PK 2 H0 4 ). [The sodium phosphate and the
corresponding potash salt give most of the fluids of the body their
alkaline reaction. The alkaline reaction of the blood-plasma is partly
due to alkaline phosphates which are chiefly derived from the food.
The acid sodium phosphate is the chief cause of the acid reaction
of the urine. A small quantity of phosphoric acid is formed in the
body owing to the oxidation of " lecithin " which contains phosphorus,
and also forms an important constituent of nerve-tissue.]
Sodium carbonate (Na 2 C03) and sodium bicarbonate (NaHCOs) [exist in small
quantities in the food, and are chiefly formed in the body from the decomposition
of the salts of the vegetable acids. They occur in the blood-plasma, where they
play an important part in carrying the CO 2 from the tissues to the lungs.]
Sodium and potassium sulphates (NaS0 4 , and K 2 S0 4 ) [exist in very small
quantity in the body, and are introduced with the food, but part is formed in the
body from the oxidation of organic bodies containing sulphur.]
[Potassium chloride (KC1 2 ) is pretty widely distributed, and it occurs specially
in muscle, coloured blood-corpuscles, and milk. Calcium fluoride (CaFl 2 ) occurs
in small quantity in bones and teeth. Calcium carbonate (CaC0 3 ) is associated
with calcium phosphate in bone, tooth, and in some fluids, but it occurs in rela-
tively much smaller amount. It is kept in solution by alkaline chlorides, or by the
presence of free carbonic acid.]
Ammonium chloride (NH 4 C1). [Minute traces occur in the gastric juice and
Magnesium phosphate (Mg 3 P0 4 ) [occurs in the tissues and fluids of the body
along with calcium phosphate, but in very much smaller quantity.]
IV. PreeAcids. Hydrochloric acid (HC1) [occurs free in the gastric juice, but
in combination with the alkalies it is widely distributed as chlorides.] Sulphuric
acid (H 2 S0 4 ) [is said to occur free] in] the saliva of certain gasteropods, as Dolium
galea, In the body it forms sulphates, being chiefly in combination with soda and
V. Bases* Silicon as silicic acid (Si0 2 ) ; manganese, iron, the last forms an
integral constituent of the blood pigment ; copper (?), p. 352.
248. (B.) Organic Compounds.
I. THE ALBUMINOUS OR PROTEID SUBSTANCES.
1. Froteids and their Allies.
r6teids and their allies are composed of C, H, 0, N, and S, and are derived
from plants (see Introduction).
[According to Hoppe-Seyler their general percentage composition is
O. H. N. C. S.
From . . . 20-9 6'9 15 -2 51 '5 0'3
to .... 23-5 to 7'3 to 17'0 to 54*5 to 2-0.]
CHARACTERS OF THE PROTEIDS. 501
They exist in all animal fluids, and in nearly all the tissues. They occur partly
in the fluid form, although Briicke maintains that the molecule of albumin exists
in a condition midway between a state of imbibition and a true solution and
partly in a more concentrated condition.
Besides forming the chief part of muscle, nerve, and gland, they occur in nearly
all the fluids of the body, including the blood, lymph, and serous fluids, but in
health mere traces occur in the sweat, while they are absent from the bile and the
urine. White of egg is the type. In the alimentary canal they are changed into
peptones. The chief products derived from their oxidation within the body are
C0 2 H a O, and especially urea, which contains nearly all the X of the proteids.
Constitution, Their chemical constitution is quite unknown. The N seems
to exist in two distinct conditions, partly loosely combined, so as to yield am-
monia readily when they are decomposed, and partly in a more fixed condition.
According to Pfliiger, part of the N in living proteid bodies exists in the form of
cyanogen. The proteids form a large group of closely related substances, all of
which are perhaps modifications of the same body. When we remember that
the infant manufactures most of the proteids of its ever-growing body from the
casein of milk, this last view seems not improbable.
Characters. Proteids, the anhydrides of peptones are colloids (p. 394), and
therefore do not diffuse easily through animal membranes ; they are amorphous
and do not crystallise, and hence are isolated with difficulty ; some are soluble and
others are insoluble in water ; they are insoluble in alcohol ; they rotate the ray of
polarised light to the left; in a flame, they give the odour of burned horn.
Various metallic salts and alcohol precipitate them from their solution, and they
are coagulated by heat, mineral acids and the prolonged action of alcohol. Caustic
alkalies dissolve them (yellow), and from this solution they are precipitated by acids.
Decompositions. When acted upon in a suitable manner by acids and alkalies,
they give rise to the decomposition products leucin (10-18 per cent.), tyrosin
(0*25-2 per cent.), asparaginic acid, glutamic acid, and also volatile fatty acids,
benzoic and hydrocyanic acids, and aldehydes of benzoic and fatty acids ; also,
indol (Hlasiwetz, Habermann). Similar products are formed during pancreatic
digestion (p. 342), and during putrefaction (p. 376).
Reactions. They are coagulated by (1) nitric acid, and when boiled there-
with give a yellow, the xanthoproteic reaction; the addition of ammonia gives a
deep orange colour.
(2) Millon's reagent (nitrate of mercury with nitrous acid); when heated with
this reagent above 60C., they give a red, probably owing to the formation of
tyrosin. [If the proteids are present in large amount, a red precipitate occurs,
but if mere traces are present only the fluid becomes red.]
(3) The addition of a few drops of solution of cupric sulphate, and the subse-
quent addition of caustic potash or soda give a violet colour, which deepens on
boiling, [or the same colour may be obtained by adding a few drops of Fehling's
(4) They are precipitated by acetic acid and potassium ferrocyanide.
(5) When boiled with concentrated hydrochloric acid they give a violet-red
(6) Sulphuric acid containing molybdic acid gives a blue colour (Frb'hde).
(7) Their solution in acetic acid is coloured violet with concentrated sulphuric
acid, and shows the absorption -band of hydrobilirubin (Adamkiewicz).
(8) Iodine is a good microscopic reagent, which strikes a brownish-yellow, while
sulphuric acid and cane-sugar give a purplish-violet (E. Schultze).
[(9) When boiled with acetic acid and an equal volume of a concentrated
solution of sodium sulphate, they are precipitated. This method is frequently
used for removing proteids from other liquids, as it does not interfere with the
presence of other substances.]
502 NATIVE ALBUMINS AND GLOBULINS.
249. The Animal Proteids and their Characters,
They have been divided into classes:
Class I. Native Albumins.
Native Albumins occur in a natural condition in the solids and fluids of the
body. They are soluble in water, and are not precipitated by alkaline carbonates,
NaCl, or by very dilute acids. Their solutions are coagulated by heat at 65 P -73C.
Dried at 40C., they yield a clear yellow amber-coloured friable mass, "soluble
albumin" which is soluble in water.
(1.) Serum-albumin, whose chemico-physical characters are given at p. 49,
and its physiological properties at 41. Almost all its salts may be removed
from it by dialysis, when it no longer coagulates with heat (Schmidt). It is
coagulated by strong alcohol, and is easily dissolved in strong hydrochloric acid.
When precipitated, it is readily soluble in strong nitric acid. It is not coagulated
when shaken up with ether. The addition of water to the hydrochloric solution
(2.) Egg-albumin. When injected into the blood-vessels or under the skin, or
even when introduced in large quantity into the intestine, part of it appears
unchanged in the urine (p. 397). When shaken with ether, it is precipitated.
These two reactions serve to distinguish it from (1). The specific rotation is
(Metalbumin and Paralbumin have been found by Scherer hi ropy
solutions in ovarian cysts; they are only partially precipitated by heat. The
precipitate thrown down by the action of strong alcohol is soluble in water.
They are not precipitated by acetic acid, by acetic acid and potassium ferro-
cyanide, by mercuric chloride, or by saturation with magnesium sulphate. Con-
centrated sulphuric acid and acetic acid give a violet colour (Adamkiewicz).
According to Hammarsten, metalbumin is a mixture of paralbumin and other
proteid substances. On being boiled with dilute sulphuric acid they yield a
reducing substance (? sugar)).
Class II. Globulins.
They are native proteids, which are insoluble in distilled water, but are soluble
in dilute saline solutions, sodium chloride of 1 per cent., and in magnesium sulphate,
These solutions are coagulated by heat, and are precipitated by the addition of a
large quantity of water. Most of them are precipitated from their sodium chloride
solution by the addition of crystals of sodium chloride, and also by saturating
their neutral solution at 30 with crystals of magnesium sulphate. When acted
upon by dilute acids, they yield acid-albumin, and by dilute alkalies, alkali-
(1.) Globulin (Crystallin) is obtained by passing a stream of C0 3 through a
watery extract of the crystalline lens.
(2.) Vitellin is the chief proteid in the yolk of egg. It is also said to occur
in the chyle (?) and in the amniotic fluid (Weyl). Both of the foregoing are not
precipitated from their neutral solutions by saturation with sodium chloride.
(3.) Para-globulin or Serum-globulin (P. 44).
(4.) Fibrinogen (p. 45).
(5.) Myosin is the chief proteid in dead muscle. Its coagulation in muscle
post mortem constitutes rigor mortis. If muscle be repeatedly washed and after-
wards treated with a 10 per cent, solution of sodium chloride, it yields a viscid
fluid which, when dropped into a large quantity of distilled water, gives a white
flocculent precipitate of myosin. It is also precipitated from its NaCl solution
by crystals of NaCl. For Kiihne'a method of preparation, see Muscle.
(6.) Globin (Preyer), the proteid residue of haemoglobin.
ALBUMIN ATES AND OTHER PROTEIDS. 503
Class III. Derived Albumins (Albuminates).
(1.) Acid- Albumin or Syntonin. When proteids are dissolved in the stronger
acids, e.g., hydrochloric, they become changed into acid-albumins. They are
precipitated from solution by the addition of many salts (NaCl, Na 2 S0 4 ) or by
neutralisation with an alkali, e.g., sodic carbonate, but they are not precipitated
by heat. The concentrated solution gelatinises in the cold, and is redissolved by
heat. Syntonin, which is obtained by the prolonged action of dilute hydrochloric
acid (2 per 1000) upon minced muscle, is also an acid-albumin. It is formed also
in the stomach during digestion. According to Soyka, the alkali- and acid-
albumins differ from each other only in so far as the proteid in the one case is
united with the base (metal) and in the other with the acid.
(2.) Alkali- Albumin. If egg- or serum-albumin be acted upon by dilute
alkalies, a solution of alkali-albumin is obtained. Strong caustic potash acts upon
white of egg and yields a thick jelly (Lieberkiihn). The solution is not precipitated
by heat, but is precipitated by the addition of an acid.
(3. ) Casein is the chief proteid in milk (p. 466). It is precipitated by acids and by
rennet at 40C. In its characters it is closely related to alkali-albuminate, but,
according to 0. Nasse, it contains more N. It contains a large amount of phos-
phorus (0*83 per cent.). It may be precipitated from milk by diluting it with
several tunes its volume of water and adding dilute acetic acid, or by adding
magnesium sulphate crystals to milk and shaking vigorously. Owing to the large
amount of phosphorus which it contains, it is sometimes referred to the nucleo-
albumins. When it is digested with dilute HC1 (O'l per cent,) and pepsin at the
temperature of the body, it gradually yields nuclein.
Class IV. Fibrin.
For fibrin, see p. 39, and for the fibrin-factors, p. 43.
Class V. Peptones.
For peptones and propeptones, see p. 331.
Class VI. Lardacein and Other Bodies.
There fall to be mentioned the "yelk -plates," which occur in the yelk:
Ichthin (cartilaginous fishes, frog) ; Ichthidin (osseous fishes) ; Ichthulin (salmon) ;
Emydin (tortoise Valenciennes and Fremy); also the indigestible Amyloid substance
(Virchow) or lardacein, which occurs chiefly as a pathological infiltration into various
organs, as the liver, spleen, kidneys, and blood-vessels. It gives a blue with iodine
and sulphuric acid (like cellulose), and a mahogany-brown with iodine. It is
difficult to change it into an albuminate by the action of acids and alkalies.
Class VII. Coagulated Proteids.
When any native albumins or globulins are coagulated, e.g., at 70C., they yield
bodies with altered characters, insoluble in water and saline solutions, but soluble
in boiling strong acids and alkalies, .when they are apt to split up. They are
dissolved during gastric and pancreatic digestion to produce peptones.
Appendix : Vegetable Proteid Bodies.
Plants, like animals, contain proteid bodies, although in less amount. They
occur either in solution in the juices of living plants or in the solid form. In com-
position and reaction they resemble animal proteids. Vegetable proteids have fre-
quently been obtained in a crystalline form (Radlkofer), e.g., from the seeds of
the gourd (Griibler) and various oleaginous seeds (Ritthausen).
504 VEGETABLE PROTEIDS.
1. Vegetable albumill is found dissolved in most juices of plants and closely
resembles animal albumin. If the dough of wheat be washed with water, and the
starch be allowed to subside, on boiling the supernatant fluid the vegetable
albumin is coagulated.
2. Glutin (vegetable fibrin) occurs in cereal grains, and its peculiar glutinous
or sticky characters, when mixed with water, enable it to form dough. From
wheat, which may contain as much as 17 per cent., it is prepared by washing away
all the starch from the dough with a stream of water. This is best effected by
washing the dough in a muslin bag or over a tine sieve. It is elastic, gray, insol-
uble in water and alcohol, and soluble in dilute acids (1 HC1 per 1000), and in
alkalies. Glutin is a complex substance. If it be boiled with water a sticky
varnish-like mass is obtained, glladin (animal gelatin). If this substance is
treated with strong alcohol it dissolves, but a slimy body remains undissolved,
mucedin. If glutin be digested with alcohol, a brownish-yellow substance, glutm-
fibrin (Ritthausen) is extracted from it.
3. Vegetable casein occurs specially in the leguminosse. It is slightly soluble
in water, but readily soluble in weak alkalies, and in solutions of basic calcic
phosphate. These solutions, like animal casein, are precipitated by acids or
rennet. The varieties of it are (a) Legumin in peas, beans, lentils (Einhof, 1805);
it has an acid reaction, is insoluble in water, easily soluble in dilute alkalies, and
in very dilute HC1 or acetic acid; (6) the casein-like body occurring in hops and
almonds which closely resembles (a), and is called conglutin (Ritthausen). Vegetable
casein, like animal casein, is an alkali-albuminate, and is precipitated by the same
substances; it is not precipitated by boiling. When long exposed to the air, its
solution coagulates with the formation of lactic acid.
250. (2.) The Albuminoids.
These substances closely resemble true proteids in their composition and origin,
and are amorphous non-crystalline colloids; some of them do not contain S, but
the most of them have not been prepared free from ash. Their reactions and
decomposition products closely resemble those of the proteids; some of them pro-
duce, in addition to leucin and tyrosin, glycin and alanin (amido-propionic acid).
They occur as organised constituents of the tissues and also in a fluid form. It is
unknown whether they are formed by oxidation from proteid bodies or by
] . Mucin is the characteristic substance present in mucus. It contains no S.
That obtained from the sub-maxillary gland contains C. 52 '31, H. 7 '22, N. 1T84,
0. 28 '63 (Obolensky). It dissolves in water, making it sticky or slimy, and can be
filtered. It is precipitated by acetic acid and alcohol ; and the alcohol precipitate
is again soluble in water. It is not precipitated by acetic acid and ferro -cyanide of
potassium, but HN0 3 and other mineral acids precipitate it (Scherer). It occurs
in saliva (p. 292), in bile, in mucous glands, secretions of mucous membranes, in
mucous tissue, in synovia, and in tendons (A. Rollet). Pathologically it occurs
not unfrequently in cysts ; in the animal kingdom, especially in snails and in the
skin of holothurians (Eichwald). It yields leucin and 7 per cent, of tyrosin when
it is decomposed by prolonged boiling with sulphuric acid.
2. Nuclein (Miescher p. 409) C. 29, H. 49, N. 9, P. 3, O. 22, is slightly
soluble in water, easily in ammonia, alkaline carbonates, strong HN0 3 ; it gives
the biuret-reaction ; no reaction with Millon's reagent ; when decomposed it yields
phosphorus. It occurs in the nuclei of pus and blood-corpuscles (p. 36), in
spermatozoids, yelk-spheres, liver, brain, and milk, yeast, fungi, and many seeds.
Its most remarkable characteristic is the large quantity of phosphorus it contains,
nearly 10 per cent. Hypoxanthin and guanin have been obtained as decomposition
products from it (Kossel),
3. Keratin occurs in all horny and epidermic tissues (epidermic scales, hairs,
nails, feathers)- C. 50'3-52-S ; H. 6-4-7 ; N. 16-2-177 ; O. 20-8-25 ; S. 07-5 per
cent., is soluble only in boiling caustic alkalies, but swells up in cold concentrated
acetic acid. When decomposed by H 2 S04 it yields 10 per cent, leucin and 3 '6 per
4. Fibroin is soluble in strong alkalies and mineral acids, in ammonio-
sulphate of copper ; when boiled with H 2 S0 4 it yields 5 per cent, tyrosin, leucin,
and glycin. It is the chief constituent of the cocoons of insects and threads of
5. Spongin, allied to fibroin, occurs in the bath-sponge, and yields as decom-
position products, leucin and glycin (Stadeler).
6. Elastin, the fundamental substance in elastic tissue, is soluble only
when boiled in concentrated caustic potash (C. 55-55 '6 ; H. 7-1-77 ; N. 16-1-177;
0. 19 '2-21 ! per cent. ) It yields 36-45 per cent, of leucin and | per cent, of tyrosin.
7. Gelatin, obtained from connective-tissues by prolonged boiling with