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- AVislicenus, Ann. d. Chem. Leipzig, 1873, Bd. clxvii. S. 302.

^ Siegfried, Bcr. d. dciitsch. chem. Gcsellsch., Berlin, 1889, S. 2711.

■* On lithium lactates, see Hoppe-Seyler and Araki, Ztschr. f. physiol. Chem., Strassburg,
1895, Bd. XX. S. 36.5.

•' Heintz, Ann. d. Cliem., Leipzig, 1871, Bd. clvii. S. 314.

^ Gscbleidlen, Arch. f. d,. ges. Physiol., Bonn, 1873-4, Bd. viii. S. 71.

' Liebig, Ann. d. Chem., Leipzig, 1847, Bd. Ixii. S. 326 ; "Wislicenus, ihld., S. 302.

* Gaglio, Arch. f. Physiol., Leipzig, 1886, S. 400; Irisawa, Ztschr. f. j)hysiol. Chem.,
Strassburg, Bd. xvii. S. 340.

" Spiro, Ztschr. f. -physiol. Chem., Strassburg, 1877, Bd. i. S. Ill; v. Frcy, Arch. f.
Physiol., Leipzig, 188.5, S. 5.57.

1'^ Colasanti and Moscatelli, JaJiresh. u. d. Fortschr. d. Thier-Chem., Wiesbaden, 1887,
S. 212 ; Marcus, Arch. f. d. ges. Physiol., Bonn, 1886, Bd. xxxix. S. 425.

^^ Araki, Ztschr. f. 'physiol. Chem., Strassburg, Bde. xv., xvi., xvii., and xix.

^' iliukowski, Ccntralhl. f. d. mcd. JFisscnsch., Berlin, 1885, No. 2 ; Arch./, exper. Path,
u. Pharmakol., Lei[izig, 1886, Bd. xxi. S. 40 ; Marcuse, loc. cit.; Nebeltlian, Ztschr./. Biol.,
Miinchen, 1889, Bd. xxv. S. 123.



THE EXTRACTIVES OF MUSCLE.



107



Calcium sarcolactate, Ca(C3H50o).2 + 4 or 4|- HgO. Soluble in 12 '4 parts
of cold water and in all proportions of boiling water or alcohol.
These salts are levorotatory, though the free acid is dextrorotatory.




Fig. 18. — Zinc sarcolactate. — After Kiihne.



(c) Levorotatory lactic acid. This is produced by the fermentation
of cane-sugar by means of a
special kind of bacillus/ and
is also found in cultures of
Gaffky's typhoid bacillus in
a solution of sugar and pep-
tone.2 Very little is known
about it yet.

In all cases where three
isomerides exist, as in the
present case' — one optically
inactive, one levorotatory,
and the third dextroro-
tatory — it should be under-
stood that strictly speaking
there are only two isomer-
ides, one dextro- the other
levorotatory, the third or
inactive variety being a com-
pound of the other two.
This was first shown by

Pasteur ^ in connection with racemic acid, which is optically inactive.
By appropriate methods of crystallisation it can be separated into two
varieties of tartaric acid, one dextrorotatory, the other levorotatory.

Another method of separating
an optically inactive material into 1 \ [

its optically active components,
has been alluded to on p. 32, in
connection with glutaminic acid
and leucine. It consists in allow-
ing moulds, like Penicillium
glauciim, to grow in a solution of
the inactive compound ; one only
of its active components is des-
troyed by the mould, and the
other remains untouched. In the
case of optically inactive lactic
acid, the question has been
attacked by the method of
crystallisation of various of its
compounds, particularly of those
with strychnine, and also of zinc ammonium lactate.'^

The mode of formation of lactic acid in muscles has been the subject
of numerous researches. That the acid is sarcolactic acid has been

^ Scliardinger, Monatsh. f. Chcm., Wien, Bd. xi.

" Blaclistein, Arch, de sc. hiol., St. Petersbourg, tome i. p. 199.

^ Ann. de. chim., Paris, Ser. 2, tome xxiv. p. 442 ; xxviii. p. 56 ; ConijJt. rend. Acad,
d. sc, Paris, tome xxxvi. p. 26 ; xxxvii. p. 162 ; Ann. d. Phys. u. Chcm., Leipzig, Bd.
Ixxx. S. 127 ; xc. S. 498, 604.

■* Purdie and "Walker, Trans. Chcm. Soc. London, 1892, p. 754 ; 1893, p. 1143.




:3»»*i



Fig




Calcium sarcolactate.' — After Kiihne.



loS THE CHEMISTRY OF THE TISSUES AND ORGANS.

stated b}^ Berzelius/ Du Bois-Reymond,^ Kiihne,^ and Heidenhain.* It
may be readily detected iii an ethereal extract by Uffelmann's reaction.^
Lactic acid is formed, not only after death, but also on activity
during hfe ; it is doubtless one of the acid products the accumulation
of which produces fatigue,^ though the possibilities of basic products
being also produced and causing fatigue by their influence on the
central nervous system should not be overlooked.'^

A number of recent researches have, however, thrown doubt on the ques-
tion whether any free lactic acid is actually formed under these circumstances.
In determining this question, it is very important to know the indicator
employed in the investigation ; hut even with the same indicator the results
obtained by different workers are sometimes discordant. One of the best
indicators for detecting weak acids is phenolphtalein.

Moleschott and Eattistini^ found a rise of acidity during rigor, while
Blome^ did not. Warren^'' finds in fatigue that the acidity is increased,
hut that the number of acid molecules is diminished. This is explained by
supposing that in resting muscle the anhydride, and in contracting muscle
the free acid, is present, Avhich latter combines with twice as much base as
the anhydride.

Gleiss ^^ agrees with the generally accepted view, that the acidity of contract-
ing muscle is due to lactic acid, and finds that the slowly contracting red
muscles of the rabbit, or the very slowly contracting muscles of the tortoise,
become acid less rapidly than ordinary voluntary muscles.

Weyl and Seitler ^^ were the first to point out that the increase of acidity
may be at least in part due to acid potassium phosphate, produced from the
alkaline phosphate by the development of neAV phosphoric acid from organic
compounds, like lecithin and nuclein. Irisawa ^^ takes a similar view in
reference to the acidity of dead organs like the liver and pancreas. The
most careful work in this direction, however, is that of Rohmann.^'^ He used
lacmoid and turmeric as indicators, and found that fresh muscle is alkaline to
lacmoid, and neutral or weakly acid to turmeric. During tetanus and rigor,
the alkalinity to lacmoid decreases, and the acidity to turmeric increases. He
attributes the acid reaction to monopotassium phosphate (KH^PO^), and
the alkaline reaction to dipotassium phosphate (KgHPO^), and to sodium
bicarbonate. If lactic acid is formed, none is free. He admits that ether
will extract lactic acid from muscle, but it will do so from alkaline muscle,
and is produced by monopotassium phosphate turning it out of combination
during the process of extraction.

With regard to the origin of lactic acid, 0. Nasse believes it comes
from the glycogen. This is the simplest view of the matter to take,
and it is supported by some work of Ekunina.^^ Many facts, however,
do not fit in with this explanation ; and the view very generally held

^ "Lehrbucli d. Cheni.," vol. vi. p. 557.

- "Gesammelte Abhandl. zur allgemein. Muskel imd Nerven Physik," Leipzig, 1877.

^ "Uutersuch. ii. das Protoplasma," Leipzig, 1864.

^ "Meclaanische Leistung," Leipzig, 1864, S. 143.

^ A dilute solution of ferric chloride and carbolic acid, which is violet, is turned yellow
by a trace (1 in 10,000) of lactic acid {Ztschr. f. klin. Med., Berlin, Bd. viii. S. 392).

^Ranke, "Tetanus." Leipzig, 1865, p. 350.

■^ A. Mosso, Trans. InUrnat. Med. Cong., Berlin, 1890.

* ArcJi. ital. dc. hioL, Turin, vol. viii. p. 90.

" Arch. f. cxper. Path. u. PharmaJcol., Leipzig, 1890, Bd. xxviii. S. 113. Blome's
results have been much criticised by Rohniann ; Arch. f. d. ges. Physiol., Bonn, 1892, Bd.
1. S. 84, iUd.. 1893, Bd. Iv. S. 589.

" Arch./, d. ges. Physiol., Bonn, BJ. xxiv. S. 39L " Ibid., Bd. xli. S. 69.

1" Ztschr. f. 2^hysiol. Chcm., Strassburg, Bd. vi. S. 557. " Ibid., Bd. xvii. S. 340.

" Loc. cit. 15 Journ.f. praJct. Chem., Leipzig, IST.F., Bd. xx.



INORGANIC CONSTITUENTS OF MUSCIE. 109

is that the acid arises from the decomposition of complex molecules,
of which proteid forms a part. It is quite possible that the lactic acid
may originate in both ways.

The idea that the acid has a proteid origin was mooted by Kiihne ^
in some of his earliest observations. He showed that not only is the
acid formed during rigor mortis, but also during the heat-coagulation of
myosin. Bohm ^ supported the proteid origin of lactic acid, and his view
was endorsed by Hoppe-Seyler.^ Some of my own experiments showing
the development of acid during the coagulation of pure myosin,^ and
Latham's theoretical views ^ on the constitution of the proteid mole-
cule, tend in the same direction. Araki*" found that diminution of
oxidation in the body, such as is produced by the inhalation of carbonic
oxide, leads to the appearance of lactic acid (and sometimes albumin
and sugar) in the urine. This is accompanied by increase in proteid
katabolism ; and this again, as Hammarsten '^ points out, is in favour of
the same view.

Inorganic constituents of muscle. — The total ash is from 1 to 1'5
per cent. In it may be noted the predominance of potash among the
bases, and of phosphoric acid among the acids. The following analyses
are by Bunge : ^ —

In parts per 1000.





I.


II.


K20


. 4-654


4-160


Na.,0


. 0-770


0-811


CaO ■ .


. 0-086


0-072


MgO


. 0-412


0-381


Fe.303 .


. 0-057




P2O5 •


. 4-644


4-58


CI


. 0-672


0-70


SO3 . .




0-10



More recent work on this question is by J. Katz.^ The flesh of a
large number of animals was investigated. The following figures give the
minimum and maximum in 1000 parts of fresh flesh ^ — :K, 2-4 to 4-6 ; JS^a, 0-3
to 1-5; Fe, 0-04 to 0-25; Ca, 0-02 to 0-39; Mg, 0-18 to 0-37: P (from
phosphates), 1-22 to 2-04 ; (from lecithin), 0-13 to 0-48 ; (from nuclein), 0-09 to
0-32 ; CI, 0-32 to 0-8.

Chemical changes accompanying the contraction of muscle —

The physiology of muscular contraction, the influence of muscular
work in metabolism, the gases of muscle, and other problems, will be
studied in other portions of this work. It may not be inappropriate here,
however, to conclude this section by stating briefly the main facts,
having a chemical bearing, relating to changes accompanying muscular
contraction. The changes are in kind similar to those which occur in

^ Arch.f. Anat. u. Physiol., Leipzig, 1859, S. 795 ; " JMyologische Untersuch.," Leipzig,
1860, p. 184.

^ Arch. f. d. ges. Physiol., Bonn, Bd. xxiii. S. 44. In a later paper {Hid., 1890, Bd. xlvi.
S. 265) Bohm reaifirms his position in reference to some criticisms of Werther (ibid., S. 53).

=* "Physiol. Chem.," S. 666, 667.

■* Journ. Physiol., Cambridge and London, 1887, vol. viii. p. 154. Tliese results, how-
ever, are criticised by v. Fiirth.

5 Brit. Med. Journ., London, 1886, vol. i. p. 630.

^ Loc. cit. (Note 11, p. 106).

^ "Physiol. Chem," 3rd German edition, S. 332.

^ Ztschr. f. physiol. Chem., Strassburg, Bd. ix. S. 60.

» Arch.f. d. ges. Physiol., Bonn, 1896, Bd. Ixiii. S. 1-85.



no THE CHEMISTRY OF THE TISSUES AND ORGANS.

muscles dm^iiig so-called rest ; there is an exaggeration of the normal
" chemical tone " of the tissue, and an explosive liberation of energy.

1. Change in reaction. — The muscle becomes acid ; this is generally
believed to be due to the production of sarcolactic acid. The views
of Eohmann and others in relation to this question (see p. 108) deserve,
however, careful consideration.

2. Changes in the proteicl. — There is no marked and immediate
increase of urea in muscular activity, though recent work tends to show
that proteid katabolism is increased, and that the increase in urea
leaves the body the next day or the day after. The main work,
however, appears to fall on the non-nitrogenous part of the muscle, as
evidenced by the immediate and large increase in the amomit of
carbonic anhydride that leaves the muscle. Hermann's theory of
muscular contraction assumes that the change is similar in kind to that
which occm-s on death, though less in degree. On death, he assimies
that the hypothetical molecule he terms inogen ^ is split into carbonic
anhydride, sarcolactic acid, and myosin. But anything like the
formation of a clot of myosin has never been observed in hving con-
tracting muscle.

3. Changes in the extractives. — During tetanus the extractives
soluble in water decrease, and those soluble in alcohol increase.^
This appears to be chiefly expHcable by the disappearance of glycogen,
and appearance of sugar and lactic acid.

4. Changes in the gases. — Hermann's theory just referred to was
largely the outcome of his failure to discover oxygen among the gases
of muscle. The oxygen used in the formation of carbonic anhydride
must therefore be held in complex union within the muscle. On
contraction, as on the occm-rence of rigor mortis, the amount of
carbonic anhydride given off is increased. The amount of oxygen
absorbed from the blood is also raised, but not in proportion ; hence the

p , . carbonic anhydride exhaled • /o„„ -c n << x) • 4 - "\

fi^^^^io^ o^^genibsoS^d ^^^^- ^^®® ^^°^'® ^^^^^^ Eespn-ation )•

5. Production of reducing substances. — Eesting muscle oxidises
pyrogallic acid ; tetanised muscle does not. A solution of nitrites
passed through contracting muscle is changed into one of nitrates, and
the colour of solutions of indigo sulphate is altered in the same
way as by reducing agents.^ A. Schmidt* arrived at the same
conclusion from the examination of the venous blood of tetanised
muscle, but what the reducing substances are that are produced is
quite unknown.

Electrical organs. — From the torpedo organ, Weyl^ extracted,
probably from the mucous fluid between the plates, a " torpedo mucin."
This, however, yields no reducing sugar. A small quantity of gelatin
and a globulin (coagulated by heat at 55°- 60°) were also obtained.^
The' tissue, like muscle, becomes acid and less transparent after

^ The nearest approach to Hermann's theoretical substance, inogen, is SiegfrieiTs phospho-
carnic acid (see p. 103).

- Helmholtz, Arch. f. Anat. ii. Physiol., Leipzig, 1845, S. 72; Ranke, "Tetanus,"'
Leipzig, 1865 ; Heidenhain, Arch. f. d. gas. Physiol., Bonn, Bd. iii. S. 574.

^ Griitzner, ibid., Bd. vii. S. 255 ; Gscheidlen, ibid., Bd. viii. S. 506.

■* Sitzungsh. d. 7c. Alcad. d. Wissenscli., Wien, Bd. xx.

^ Ztschr. f. 2)hysiol. Chem., Strassburg, Bd. vi. S. 525.

** Kriikenberg was unable to obtain myosin ("Weitere Untersueh. zur vergleich.
Muskelchem." Vergleich. physiol. Studien, 2 Reihe, Abth. 1, S. 143-7).



THE SKELETAL TISSUES. iii

death.i Weyl ^ found the percentage of water in the muscles of
torpedo to be 77"5 ; in the electrical organ, 89. He was also able to
separate a number of organic substances from the organ, similar to
those occurring in muscle and nerve, such as creatine, xanthine,
lecithin, fat, cholesterin, fatty acids, and inosite. Frerichs and
Stadeler found urea. In another research, Weyl ^ found that excitation
of the organ produced an increased formation of phosphoric acid in it.



The Skeletal Tissues.

Most of the chemical sul)stances occurring in the connective tissues
(collagen, elastin, mucin, fat) have been already described (see pp. 69-72).
There are still a few to be discussed, which will be most conveniently
done under the heads — Bone, Tooth, Cartilage, and Notochord.

Bone. — Bone differs from most other tissues in its high percentage of
mineral matter. It contains 46 "7 per cent, of water ,^ of which Aeby ^
considers 11 or 12 are in a state of loose chemical combination,
analogous to water of crystallisation.

The composition of undried bone without separation of marrow or
blood is given by Hoppe-Seyler thus : — ■



Water, 50-00 per cent.
Fat, 15-75 „



Ossein, 11-40 per cent.
Bone earth, 21-85



Zalesky's analyses of dried macerated bone are as follows : —





Human Bone.


Bone of Ox.


Bone of Guinea-Pig.


Organic constituents .
Inorganic ,,


34-56
65-44


32-02

67-98


34-70
65-30



Fossil bones analysed by Fremy'' show a smaller percentage of
organic matter.

The organic constituents of bone are ossein or collagen, small quantities
of elastin from the hning of the lacunae and canaliculi,^ proteids, and
nuclein from the cells, and a small quantity of fat even after the removal
of all the marrow. The absence of mucin in compact bone is noteworthy,
showing that the ground substance is entirely replaced by calcareous
matter.^ Marrow, however, yields mucin.^ The inorganic constituents
of bone are calcium phosphate, calcium carbonate, calcium chloride,
calcium fluoride, magnesium phosphate, and small quantities of sulphates
and other chlorides.

1 Boll, Arch. f. Anat. u. Physiol., Leipzig, 1893, S. 99 ; Du Bois-Reymond found
that the electrical organ of 3fala2Jterurics also becomes acid on activity.

^ Monatsb. d. k. Akad. d. Wissensch. , Berlin, April 1881.

^ Arch. f. Anat. u. Physiol., Leipzig, 1884, Physiol. AUh., S. 316.

* Lukjanow, Ztschr. f. physiol. Chem., Strassburg, Bd. xiii. S. 339.

^ Centralbl. f. d. mcd. Wissensch., Berlin, 1871, No. 14.

'^ Ann. de chim., Paris, Ser. 3, tome xliii. p. 47.

'' This substance is not keratin, as Brosicke supposed. See H. E. Smith, Ztschr. f.
Biol. , Miinchen, Bd. xix. S. 469.

^11. A. Young, Journ. Physiol., Cambridge and London, 1892, vol. xiii. p. 803.

® Rustiksky, Centralbl. f. d. med. Wissensch., Berlin, 1872, S. 562.



112 THE CHEMISTRY OF THE TISSUES AND ORGANS.

From a large number of analyses, Hoppe-Seyler gives the following
figures representing percentages of the total ash : —

Ca. PO,. CO 3. ri. Mg. CI.

38-49 54-46 6-24 1-28 0-44 0-19

From his own numbers, Zalesky has calculated the probable composition
of the mineral constituents of bone as follows : —

Calcium phosphate . . . 83 "889

„ carbonate . . . 13-032
Calcium in combination with fluorine,

chlorine, etc. .... 0-350

Fluorine 0-229

Chlorine 0-183

Hoppe-Seyler considered that the characteristic inorganic ingredient of
bone, dentine, and enamel is one analogous to apatite. Apatite has the
formula CajQFl2(P0J^., or Ca^QCl,,(PO^)Q. Very small quantities of these
substances, however, occur in bone ; the chief compound is one in which CO3
takes the place of the Fig or CU, namely, Ca^QC03(P04)^3. See, however,
Gabriel's researches below.

Tooth. — The calcareous tissues of tooth are dentine, enamel, and
crusta petrosa. The last named is bone ; dentine is chemically similar
to bone. Enamel, though epithelial in origin, may be conveniently
taken here.

Dentine. — This consists of water 10 per cent., and solids 90 per cent.
The solids are organic and inorganic. The organic solids are less
abundant than in l)one. They consist of collagen and elastin ; the latter
form the lining of the dentinal tubules. From Aeby's analyses, Hoppe-
Seyler gives the following taljle : — •

CaioC03(P04)e . . . 72-06 per cent.
MgH(P04) .... 0-75 „
Organic substances . . 27-70 ,,

Enamel. — This is the hardest tissue in the body. Hoppe-Seyler's
quantitative analyses give the following mean result : —

CaioC03(P04)^ . . .96-00 per cent.
MgHPO^ . . . .1-05
Organic substances . . 3-60 ,,

Various other investigators give numbers varying from 2 to 10 per
cent, of organic matter. This they estimate by loss on ignition. Tomes,^
however, has recently shown that this loss is chiefly if not wholly due
to water. On attempting to estimate the organic matter directly,
none was found, or a quantity too small to be weighed.

Gabriel '^ has recently worked at the question of the constitution of
the mineral matter of bones and teeth. Some of his conclusions do
not accord with the older work of Hoppe-Seyler. He finds that the
constituents are water, lime, magnesia, potash, soda, phosphoric acid,
carbonic anhydride, chlorine, and fluorine. The quantities of lime
and phosphoric acid, which are the most abundant constituents, vary

^ Journ. Physiol., Cambridge and London, 1896, vol. xix. p. 217 ; I'rans. Odoat. Soc.
Gr. Brit, London, 1896. p. 114.

'^ Ztsdir. f. 'physiol. Chem., Sti'assburg, J3d. xviii. S. 257.



CARTILAGE. 113

but little, and are proportional to each other ; the amounts of magnesia
and carbonic anhydride are also proportional the one to the other.
The amount of potash is greater than that of soda. The amount of
chlorine is very small, and is greater in the teeth (0-21 per cent.) than
in bone. Fluorine is a minimal constituent of both ^ ; as a rule, not
more than 0'05 per cent, is present.

Water is present in two forms ; one part passing off at 300°-350° C.
is similar to water of crystallisation ; the other part is only expelled by
fusion with silicic acid, and is an expression of the basicity of the
phosphate, and is called water of constitution or acidic water.

The composition of the ash finds its simplest expression in the
formula, Ca3(P04)2+Ca5HP30i3+Aq, in which 2 to 3 per cent, of
the lime is replaced by magnesia, potash, and soda, and 4 to 6 per cent,
of the phosphoric acid by carbonic anhydride, chlorine, and fluorine.
The limit of variation is, however, small, and the differences between
bone ash and tooth ash are not greater than those between the ash of
different bones.

The notocliord. — Sternberg ^ found that neither gelatin nor chondrin
is obtainable from the notochord, and Neumann^ that the cells stain
with iodine as though they contained glycogen. Kossel ^ obtained a con-
siderable supply of material from large lampreys, and found that it
contains 95-96 per cent, of water ; this contrasts strongly with cartilage,
and corresponds with what one finds in other embryonic tissues. The
amount of ash is 0-85 per cent. The amount of glycogen constitutes
from 12 to 15 per cent, of the solids present ; the high percentage of
this substance is another feature common to embryonic structures.
There is not much more than a trace of proteid matter soluble in water.
Gelatin, collagen, and mucin are all absent ; the bulk of the solid matter
is an insoluble proteid easily digested by artificial gastric juice ; it yields
no sugar on treatment with mineral acids.

Cartilage. — The following analyses by Hoppe-Seyler exhibit the
relative proportions of the chemical constituents of human hyaline
cartilage. In 1000 parts —

Costal Cartilage. Articular Cartilage.

Water 676-6 735-9

Solids 323-3 264-1

Organic soHds . . 301-3 248-7

Inorganic solids . . 22-0 15-4

Potassium sulphate (in a hundred parts of ash) . 26-66



Sodium sulphate
Sodiiim chloride
Sodium phosphate
Calcium phosphate
Magnesium phosphate



44-81
6-11

8-42
7-88
4-55



The organic solids consist in small part of those in the cells,
which are of the usual proteid nature, together with small quantities
of fat and glycogen, demonstrable by micro-chemical means ; but the

^ For recent estimations of fluorine in bone and teeth by Carnot's method {Compt. rend.
Acad. d. sc, Paris, tome cxiv. p. 750), see Gabriel, Ztschr. f. anal. Chem., Wiesbaden,
Bd. xxxi. S. 522 ; and Waampelrneyer, ibid., Bd. xxxii. S. 550.

'^Arck.f. Physiol., Leipzig, 1881, S. 105.

•^ Arch. f. mikr. Anat., Bonn, Bd. xiv. S. 54.

'^ Ztschr. f. physiol. Chem., Strassburg, Bd. xv. S. 331.

VOL. I. — 8



1 14 THE CHEMISTR Y OF THE TISSUES AND ORGANS.

great bulk of the organic solids is derived from the matrix of the
cartilage.

In fibrocartilage, the hyaline matrix is pervaded either by white
fibres (white fibrocartilage), or by yellow fibres (yellow or elastic fibro-
cartilage).

In contrast with true bone, the analysis (Ijy Fremy) of the calcified
cartilage of the ray may be here given : —

Ash per cent. . . . SO'OO j Calcium carbonate . . 4*3
Calcium phosphate . . 27*7 | Magnesium phosphate, traces.

The matrix of hyaline cartilage. — The organic basis of the matrix was
formerly described as chondrigcn; and just as gelatin is obtained from
collagen on boiling, so chondrin is obtained by boihng chondrigen.
Chondrin, like gelatin, gelatinises on coohng a solution of it made with
warm water, but in many of its reactions it differs from gelatin.

Elementary analyses of chondrin, however, showed very great dis-
crepancies, and Morochowetz ^ arrived at the conclusion that chondrin is
not a chemical unit but a mixtiu'e of gelatin and mucin. This conclusion
has been more recently amphfied by C. T. Morner,^ who worked under
the superuitendence of Hammarsten.

The matrix contains four substances — (1) collagen, (2) an albuminoid,
(3) chondromucoid, and (4) chondroitin-sulphuric acid. Of these con-
stituents the last two, with perhaps a little collagen, he around the cells,
forming what Morner calls chondrin balls ; they correspond to the mucin
of Morochowetz, or hyalogen of Krukenberg, and are coloured blue by
methyl-violet. They Lie in the meshes of a network composed of collagen
and mucoid, which is stainable by tropaolin.

These foiu' constituents may be separated as follows. The mucoid



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