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C0H5.NH— N N— NH.CgHs

(osazone) (hydrogen) (water)

The hydrogen seen in the second equation is not really set free, but
it is used to split up a further molecule of phenylhydrazine into aniline and
ammonia (NH,— NH.C.H, + H, = NH.C^H^ + NH^).

In order to obtain the sugar from the osazone again, it is first
treated with fnming hydrochloric acid.^ This gives rise to phenylhy-
drazine and a so-called osonc. An osone is a substance which, besides
the ketone group, contains an aldehyde group as well : CH^OH — (CH.0H)3
—CO— COH.

By means of zinc and acetic acid the osone is easily reduced to sugar.

Glucosamine. — A derivative of glucose which is of some pliysiological
interest is amido-glucose or glucosamine, C^H^^Of^.NHg. This is obtained on
the decomposition of chitin and chondroitin. By treatment with nitrous acid
it passes into dextrose —

C,H,,0,.NH2 4- Is^OOH = C.HioOe + N. + H.O

Glucosamine can also be obtained by treating phenylglucosazone directly with
reducing agents —

C,3HioO,.(N2H.CeH5)2 4- H.O + H, = CoHiiOs-NHo -t-

(phenylglucosazone) (glucosamine)

NH.— Is^H.CeHj -J- NH,C,H,

(phenylhydrazine) (aniline)

This shoAvs us another way of regenerating the sugars from their osazones."-^
Further particulars about glucosamine will be found in connection with chitin
and cartilage.

The disaccharid.es. — A disaccharide is a condensation product of
two molecules of the simple sugars or monosaccharides, the change being
attended with the loss of a molecule of water : —

C,H,,,06 + C^HioO, = C,,Ho,Oii + HP
Thus^

Cane-sugar is derivable from dextrose and levulose ;
Milk-sugar, or lactose, from dextrose and galactose ;
Maltose, from dextrose and dextrose.

The general properties of these sugars are like those of the monosac-

1 E. Fischer, -5cr. d. dcutsch. chem. Gesdhch., Berlin, 1888, Bd. xxi. S. 2631; 1SS9,
Bd. xxii. S. 87 ; 1890, Bd. xxiii. S. 2118.

- E. Fischer, ibid., Berlin, Bd. xix. S. 1920 ; Fischer and J. Tafel, ibid., Bd.
XX. S. 2569.



lo CHEMICAL CONSTITUENTS OF BODY AND FOOD.

charides ; their solubilities are similar ; they are optically active,
crystallisable, diffusible, and sweet. Heated dry, they give rise to
caramel. Further, they (with the exception of cane-sugar) reduce
alkaline solutions of metallic oxides like Fehling's solution, and (again
with the exception of cane-sugar) form crystalline osazones.

By hydrolysing agencies they take up water, and split into the simple
sugars of which they are made up. Thus —

Cane-sugar + water = dextrose 4- levulose.
Maltose + water = dextrose -i- dextrose.
Lactose + water = dextrose + galactose.

Among the agents capable of producing this decomposition the
inverting ferment of the small intestine must be particularly mentioned.
The term inversion arose from the fact that, if cane-sugar is the sub-
stance acted on, the previously dextrorotatory solution becomes levo-
rotatory, because the levorotatory power of the levulose is greater than
the dextrorotatory power of the dextrose formed. The term inversion
has, however, been extended to include the similar decompositions of
lactose and maltose. The reverse action by which the monosaccharides
are united to form disaccharides is called reversion.

Cane-sugar is generally distributed throughout the vegetable
kingdom in the juices of plants and fruits, especially the sugar-cane,
beetroot, mallow, and sugar -maple. As a food it is of high value. After
abundant ingestion of cane-sugar, traces may be found in the blood and
urine ; but the greater part undergoes inversion in the alunentary
canal.

It is readily soluble in water (100 parts of satm^ated solution contain
67 of sugar),^ but soluble with difficulty in alcohol. It forms large,
colourless monoclinic crystals. It is strongly dextrorotatory, and
the amount of rotation does not vary so much with concentration
and temperature as do most of the other sugars. The average value
of («)^ = -+-66-5.

Cane-sugar does not give many of the sugar tests ; thus, it does not
give Moore's test ; with Trommer's test, it gives a blue solution, but no
reduction occurs on heating. It does not react with phenylhydrazine,
and it is not directly fermentable by yeast ; the yeast, however, secretes
an inverting ferment, and after inversion the glucoses formed are con-
verted into alcohol and carbonic acid.

By boiling with concentrated hydrochloric acid a deep red solution
is formed. Dextrose, maltose, and lactose do not give this reaction.

Maltose is one of the end products of the action of malt diastase on
starch. It is also the chief sugar formed from starch by the diastatic
ferments contained in the saliva and pancreatic juice. It is an inter-
mediate product in the action of sulphuric acid on starch. It crystalhses
with one molecule of water of crystallisation in fine white needles. It
is easily soluble in water and in alcohol ; insoluble in ether. It is
dextrorotatory ; but its rotatory power decreases with concentration
(relatively) and with rise of temperature.

For a 20 per cent, solution at 15° C. (a)j, = + 1:39°-3. The amoimt
of rotation is al)out 18° less for a freshly prepared solution than for one
which has stood for some liours.^

^ Scheibler, see Tolleii's " Ilaudlnioh."

- Brown, Morris, and Millar (Proc (Jlimx. Soc, London, 1SP6, p. 244) give («)u= +138".



THE DISACCHARIDES. ii

Maltose reduces copper, bisniutli, and other metallic salts in alkaline
solutions, but its reducing power as measured by I'ebling's solution is
about one-third less than that of dextrose.^ It does not reduce Barfoed's
reagent 2 as dextrose does. It ferments readily with yeast. With
phenylhydrazine, phenylmaltosazone is formed (C24H32N40n); this crystal-
lises in yellow needles much broader than those yielded Jjy dextrose or
lactose; it melts at 206^ C. Unlike phenylglucosazone, it dissolves
in seventy-five parts of boiling water, and is still more soluljle in hot
alcohol (Fig. 2).




Fig. 2. — Crystals of plieiiylmaltosazone.

Isomaltosc ^ is a sugar formed at the same time as maltose by the
action of either diastase, ptyalin, or amylopsin * on starch. It is also an

1 Ten c.c. of Fehling solution corresponds to 0-05 grnis. of dextrose, levulose, or galactose,
and to 0-07196 of maltose.

M3'3 grnis. of cupric acetate are dissolved in 200 c.c. of water; to this solution,
6 c.c. of acetic acid containing 38 per cent, of glacial acetic acid are added (Barfoed,
"Organic Analysis," p. 254).

=* Originally described by Fischer, Ber. d. cUutseli. clievi. Gesellsck., Berlin, Bd. xxiii.
S. 3687. Fischer's observations, -which haA^e been called in question by some chemists, have
been_ very generally confirmed. In his most recent ]>aper on the subject, ibid., 1896, Bd.
xxvii. S. 3024, he shows that isomaltose is not directly fermentable by yeast, and so may be
separated from maltose. Its osazone is soluble in four parts of hot water, while that from
maltose requires seventy-five parts.

■* KiUz and Vogel, Ztschr.f. Biol., Mlinchen, Bd. xxxi.



12 CHEMICAL CONSTITUENTS OE BODY AND EOOD.

intermediate product in the formation of dextrose by mineral acids from
starch. An amylolytic ferment in blood serum, capable of forming
dextrose from starch, acts similarly.^ A small quantity occurs in
normal urine.^ It is readily soluble in water, is very sweet, and
ferments slowly with yeast. Its general characters are like those of
maltose, but its osazone forms fine yellow needles which melt at 150° C.
Lactose or' milk-sugar occurs only in milk, and occasionally in the
first days of lactation in the urine in small quantities.^

It crystallises in rhombic prisms, which contain one molecule of water

of crystallisation (Fig. 3). It is soluble in six

yy / 1 parts of cold, and two and a half parts of hot

^ Lr\;j water; it is therefore less soluble than the

/vlVv\ other sugars. It has only a famt sweet

/^ Av </ r^^^ taste. Aqueous solutions are dextro-rotatory

I . ^'''^^ (a)i, = + 59°-3 (Hesse)^ and H-52°-5 for the

yy \/ C^ Q hydrate at 20° C. (Schmoger).^ Its reducing

l^ power as tested by Fehling's solution is

/ y^ intermediate between that of dextrose and

^ f maltose.*' Lactose is very resistant to the

Fig. 3. -Lactose crystals.— After inverting ferment of yeast, and so undergoes

''^•^'' the alcoholic fermentation very slowly. It

is, however, rapidly inverted by the Kephir fungus, and of all the

sugars is that most readily affected by the £. lactis; the lactic acid

fermentation occurs in two stages, as follow : —

1. C^.^H, Ai + H.O = 4C3HeO.,

(lactose) ■ (lactic acid)

2. 2C,Hq03 = C,Hs02 + 2COo + 2H2
(lactic acid) (butyric acid)

With phenylhydrazine, lactose yields phenyl-lactosazone, Mdiich readily
crystallises in needles (Fig 4). It is soluble in eighty to ninety parts
of boiling water. Its melting point is 200° C.

Among the rarer disaccharides must be mentioned trehalose (from certain
fungi), and melehiose, a saccharose Avhich with c^Z-fructose (levulose) is obtained
from raffinose. Rajjinose "^ is an interesting sugar found in Eucalyptus manna,
cotton seeds, and barley. It is a trisaccharide, consisting of a combination
of dextrose, levulose, and galactose.

The polysaccharides. — To this group belong a large number of
carbohydrates of high molecular weight, and with the formula (C(;Hi„0-)„.
Their molecular weights differ a good deal, but have not yet l)een
determined directly by chemical methods.^ They are not crystalline,
are indiffusible, and, as a rule, insoluble in cold water. In liot water
they partially dissolve, forming opalescent solutions. Like the protcids,

^Rohmann, Centrcdhl. f. d. med. Wissensch., Berlin, 1893, S. 8-19.

" Lcrnaire, Ztschr. f. jjhysiol. C'hem., Strassburg, 1896, Bd. xxi. S. 442.

' The most recent observations on lactose in the nrine of women after childbirth are by
Lemaire, Ztschr.f.ioliysiol. Chem., Strassburg, 1896, Bd. xxi. S. 442. Pavy, Lancet, London,
1897, vol. i. p. 1075. See also Hofmeister, Ztschr.f. plnjsiol. Chcm., Strassburg, Bd. i. S. 101.

* Ann. d. Chcm., Leipzig, 1875, Bd. clxxvi. S. 98.

^ Ber. d. deutsch. cJtem. GesrJhch., Berlin, 1880, Bd. xiii. S. 1922.

" Ten c.c. of Fehling's solution = 0-06334 lacto,se ; sec footnote 1, p. 11.

■^ Loiseau, Comjit. rend. Acad. d. sc, Paris, 1876, tome Ixxxii. p. 1058 ; Ber. d. deutsch.
chcm. Gesellsch., Berlin, IW. ix. S. 732 ; Sclieibler, ibid., 1886, Bd. xix. S. 2868.

^ By Raoult's method of determining the lowcsring of the freezing point in very dilute
solutions. Brown and Movrh {Journ. Chem. Soc, London, 1888, p. 610), have provisionally



THE POLYSACCHARIDES.



13



they are precipitated from their sokitions by saturation with certain
neutral salts, such as ammonium sulphate.^




Fig. 4. — Crystals of phenji-lactosazone.

By hydrolysis they are finally split up into simple sugars ; various
dextrins and disaccharides being intermediate products. The dextrins
are of various kinds, and are differently named by different observers.
The reaction cannot be represented by equations with certainty as long
as the molecular weights of the members of the group are unknown.

Brown and Morris suggest the following series, indicating the successive
steps of the hydrolysis, in the case of starch under the influence of diastatic
ferments : —

(C,H,,0,)„ + H,0 = (C,Hi,0,X._, + C,3H,,0,,

(starch) (dextrin) (maltose)

(CoHioO,)„_, + H,0 = (C,H,,0,)„_, + C,,H,,0,,
(dextrin) (dextrin) (maltose)

(dextrin) (dextrin) (maltose)



assigned to dextrin and soluble starch the formulfe (C(.,Hio05);i„ and (CgHj^oOj)^^ re-
spectively. The same method applied to starch, though not so satisfactorily, points to a
molecular weight of between 20,000 and 30,000 ; that is, about three times greater than that
of soluble starch. SabanejeflF, Cliem. Ccntr.-Bl., Leipzig, 1891, S. 10 ; Journ. Russian Chevi.
Soc, vol. xxi. p. 515, by the same method assigns to glycogen the formula (Cp,Hm05)-io-

^ Pohl, Ztschr. f. 2}hysiol. Chem., Strassburg, Bd. xiv. S. 151 ; Young, " Proe. Physiol.
Soc," Feb. 1.3, 1897, in Journ. Physiol., Cambridge and London, vol. xxi.



14 CHEMICAL COXSTITUEXTS OF BODY AXD FOOD.
and so on, iintil at last we get to



and finally



(dextrin) (dextrin) (maltose)

(C,Hio05)2 + H,0 = Ci,H,„0„
(dextnn) (lualtose)



The priucipal sub-groujjs of the polysaccharides are the starch
group, the giira gi'oup, and the cellulose group. The starch groujj
includes starch, inulin, Kchenin, and glycogen. The gum group includes
the dextrins, the plant gums and mucilages, and animal gum. The
cellulose group includes cellulose, the heniicelluloses, and tunicin.

Starch is one of the most "s^idely distributed carbohydrates in the
vegetable kingdom. It occurs in natiu'e in granides, which consist of
two principal substances, starch-granulose and starch-cellulose ; of these
the former only is dissolved by the digestive juices. Erythrogranulose,
which gives a red colom- with iodine, is present in small quantities
(Briicke).

Starch is insoluljle in cold water, in alcohol, and in ether. With
hot water it swells, forming an opalescent solution or starch paste.
This, if concentrated, gelatinises on coohng. On hydrolysis it forms
first soluble starch (also called amylodextrin or amidulin), then other
dextrins, and finally maltose and dextrose.

The most characteristic reaction of starch is the blue compound it
forms with iodine.^ It does not give Trommer's test or ]\Ioore's
test, nor does it ferment with yeast. The specific rotatory power ^
of soluble starch for concentrations of 2-5 to 4-5 per cent, at 15°-5 C,

(V.)^=-r202°.

Iiiuliii is found in the roots of many composites. It is usually
prepared from dahhas. It is the only polysaccharide which can be
obtained in a crystallised form, namely, as sphero-crystaLs which
polarise light. It is readily soluljle in warm water ; by cooling the
solution it is precipitated. By hydrolysis its final jjroduct is levulose.^

Liclienin is a polysaccharide occurring in Iceland moss, and certain
algae. It is insoluljle in cold water, soluble in hot water, gives a yellow
colour with iodine, is converted into glucose by hot dilute mineral acids,
but is not affected by sahva or pancreatic juice.*

Glycogen. — This is a small but constant constituent of protoplasm,
and of animal tissues generally. It is found in white blood corpuscles,^
and in pus,^ occasionally in diabetic mine," but is specially abundant in

^ E. Zander finds that the iodine reaction given by polysaccharid&s and by chitin varies
considerably with the solvent used {Arch. f. d. ges. Physiol., Bonn, 1897, Bd. Ixvi.
S. 545).

^ BrowTi, ^lorris, and Millar, loc. cit.

3 Kulz, "Beitr. z. Path, des Diabetes. " Marburg, 1894, S. 130. ; Worm-Miiller, Arch,
f. d. rjes. Physiol, Bonn, 1884, Bd. xxxiv. S. 576 ; 1885, Bd. xxxvi. S. 172 ; F. Hofnieister,
'Arch. f. exper. Path. u. Pharmakol., Leipzig, 1889, Bd. xxv. S. 240. On " Inulin as a
Precursor of Glycogen," see Miura, Ztschr. f. Biol., Munchen, Bd. xxxii. ; he obtained
very inconstant results.

■• Nilson, Utjsala Laka/ref. Fiyrh., vol. xxviii., quoted by Hammarsten, in "Physiol.
Chem.," 3rd Gei-man edition, S. 67.

5 Salomon, DeiUsche uxed. Wchnschr., Leipzig, 1877, Xos. 8 and 35 ; Cerdndhl. f.
Physiol, Leipzig, Bd. vi. S. 512 ; Huppert, Centralbl /. Physiol, Leipzig, Bd. vi
S. 394.

^ Salomon, loc. cit.

'' Leube, Virchovfs Archiv, Bd. cxiii. S. 391.



THE POL YSA CCHA RIDES. 1 5

liver and muscle,^ in embryonic tissnes generally,^ and in the bodies of
molluscs.^ It has Ijeen described in pathological growths,* and in
the vegetable kingdom in many fungi ^ (truffles, mucor, yeast,
myxomycetes).

It may be dissolved out with boiling water (Brlicke),^ 2 per cent,
potash (Klilz),'^ or by trichloracetic acid,** from the tissues in which it
occurs. The extraction with this acid is, however, incomplete, and the
product is impure.^ Huizinga ^'^ recommends that glycogen should be
extracted from the liver by a mixture of equal parts of saturated
solution of mercuric chloride, and Esbach's reagent (10 grms. of picric
and 20 of citric acid in a litre of water). From this solution,
which is proteid free, glycogen is precipitable by alcohol.

The pure material is a white tasteless powder, soluble in water, forming
a strongly opalescent solution. It is insoluble in alcohol and in ether.
It is strongly dextrorotatory;^^ (a)jj = + 196°'63. With Trommer's test
it gives a blue solution, but no reduction occurs on boiling.

With iodine it gives a port-wine red colour, which easily distin-
guishes it from starch. Its precipitability by basic lead acetate dis-
tinguishes it from dextrin.

Prolonged boilmg with water or boiling with dilute mineral acids
converts it into sugar. The diastatic ferments act similarly.

Max Cremer i- investigated the action of dilute acids on glycogen ; he
found ghicose and isomaltose (identified by their osazones), but no maltose.
Kiilz and Vogel ^^ investigated the action of diastatic ferments ; parotid saliva
produced isomaltose and maltose in the proportion of 1 to 2 from hver-glycogen,
and isomaltose with small amounts of maltose and dextrose from muscle-
glycogen ; pancreatic juice and malt diastase produced practically the same
result. The ferment in the liver which acts on glycogen produces dextrose.

The physiological relationships of glycogen wiU be treated elsewhere.
There is much controversy on the subject of the origin and fate of glycogen.
There is, however, little doubt that it is chiefly a storage product from the
carbohydrates of the food,^'^ and that after death it is transformed into dextrose ;
the principal controversies of recent years have centred round the question
whether glycogen normally leaves the liver in the hepatic blood as sugar (as

^ Claude Bernard, Compt. rend. Acad. d. sc, Paris, 1857, tome xliv. pp. 578 and 1325 ;
xlviii. pp. 77, 68.3, 763 and 784; Hensen, Virchoiv's Jrchiv, 1857, Bd. xi. S. 395; 0.
Nasse, Arch. f. d. ges. Physiol., Bonn, 1869, Bd. ii. S. 97.

^ Claude Bernard, " Physiologie exper.," 1855, tome i. p. 241; iv. p. 44; Salomon,
Centralbl. f. d. mod. IFissensch., Berlin, 1874, S. 738; Moriggia, ibid., 1875, S. 186; v.
Wittich, Hermann's " Handbuch," 1883.

^ Bizio, Ztschr. f. Chcm., Leipzig, 1866, S. 222 ; Bernard, " Lecons snr les phenomenes
de la vie," 1879, tome ii. ; Krukenberg, " Vergl. physiol. Studien," 1880, Bd. ii. S. 52.

■* Ktihne, Virchoiv's Archiv, Bd. xxxii. S. 536 ; Sotnitscliewski, Ztschr. f. 23h>ts'ioI.
Chem., Strassburg, 1880, Bd. iv. S. 220.

^ Kiiline, " Lehrbuch der physiol. Chem.," 1868, S. 334; Reinke and Rodewald,
"Studien ueber das Protoplasma," Berlin, 1881, S. 34, 54, and 169; Errera, Bull. Acad,
roy. de med. de Bclrj., Bruxelles, Bd. iv. S. 451.

® Sitzu7igsb. d. k. AJcad. d. IFissensch., Wien, 1871, Bd. Ixiii. S, 214.

"^ Ztschr. f. Biol., Mllnchen, 1886, Bd. iv. S. 191.

8 Frankel, Arch. f. d. ges. Physiol., Bonn, Bde. lii. S. 125 ; Iv. S. 378.

9 Weidenbaum, ibid., Bde. liv. S. 319 ; Iv. S. 380.
1** Arch. f. d. ges. Physiol. , Bonn, Bd. Ixi.

^^ Huppert, Ztschr. f. jjhysiol. Chem., Strassburg, Bd. xviii. S. 137.

12 Ztschr./. Biol., Mlinchen, 1894, Bd. xxxi. S. 181. i^ Ibid., S. 108.

^■^ According to Voit and his pupils {Ztschr. f. Biol., Mlinchen, Bd. xxviii. S. 245), the
liver forms glycogen only from dextrose and levulose, or from those carbohydrates which
are converted into these sugars before they reach the liver.



i6 CHEMICAL CONSTITUENTS OF BODY AND FOOD.

Bernard originally taught), or is employed in the synthesis of fat and proteid
(as Pav}' holds).

Dextrin is the name given to a number of intermediate substances
formed during the hydrolysis of starch ; the principal varieties are
erythrodextrin, which gives a red coloiu' with iodine; achi-oodextrin, which
does not ; and maltodextrin, which has a lower molecular weight than
these.^ The dextrins are dextrorotatory (maltodextrin has an ia)^ = +
174°"5). They are soluble in water, and insoluble in alcohol and ether.
They give a blue solution with Trommer's test, but no reduction occm^s
on boiling.

Animal gum was discovered by Landwehr,- and resembles achroodextrin
and glycogen in some of its properties. It is a decomposition product of
mucin. When boiled Avith dilute sulphuric acid it yields a reducing but
unfermentable sugar. Animal gum, like the vegetable gums, gives gelatinous
precipitates with copper and iron salts.

Animal dextran is a gummy material, secreted by the Scliizoneura
lanuginosa, a gall-producing louse that attacks elms.^

Vegetable gums and mucilages include such substances as gum arable,
wood gum, etc., which are of subordinate physiological interest.

Cellulose is the name given to a number of carbohydrates which form
the chief constituent of vegetable cell walls. In old cells, where it
becomes very insoluble, it is called lignin. The celluloses are insoluble
in cold and hot water, in alcohol, ether, and dilute acids and alkalies.
A specific reagent for dissolving them is Schweitzer's reagent (a solution
of cupric hydrate in ammonia).

With iodine and concentrated sidphmic acid they are tm^ned blue ;
with nitric acid they yield nitroso-compoimds of an explosive natm^e.
Prolonged treatment with strong mineral acids leads to the formation of
sugars ; in some cases glucose, in others mannose, is formed. Schidze's
mannoso-cellulose,* found in coffee and other seeds, is not a hemicellu-
lose (see next paragraph). The celluloses are not acted upon by the
digestive ferments proper ; l^ut they may be broken up hi the intestine
by bacteria mto carbonic acid and methane.

Hemicelluloses are those varieties of cellulose which ditfer from the others
by yielding monosaccharides by treatment with dilute mineral acids. The
hemicellulose of yellow lupins yields galactose and arabinose ; that of rye and
wheat, arabinose and xylose; that of certain nuts, mannose.-^

Tunicin is animal cellulose. It is the chief constituent of the test or outer
investment of the tunicates.*^

Cellulose has also been found in the animal kingdom in the skin of the
silkworm," and in the zoocytium of OpTtrijdium versatile.^

Inosite. — Inosite is a substance found in muscle and other animal
tissues, and in many vegetables also. Its crystalline form is shown

1 Recent papers on dextrin will be found in Ber. d. deutsch. chem. Gesellsch., Berlin.
Bde. xxiii. S. 3060 ; xxvi. S. 29-30 (by Scheibler and Mittelmeier), and Bd. xxvi. S.'
2533 (by Leubuer and Doll).

- Ztschr. f. 2)hysiol. Chem., Strassburg, Bd. viii. S. 119, 124.

^ Liebermann, Arch. f. d. aes. Physiol., Bonn, Bd. xl. S. 454.

* Ztschr. f. physiol. Chem., Strassburg, Bd. xvi.

5 See Schulze, loc. cit. ; and Reiss, Bcr. d. deutsch. chem. Oe^clhch., Berlin, Bd. xxii.

*^ Schiifer, Ann. d. Chem., Leipzig, Bd. ccx. S. 312; Berthclot, Ann. de chim., I'aris,
S6r. 3, tome Ivi. p. 153.

"^ De Lucca, ComjJt. rend. Acad. d. sc, Paris, tome lii. p. 102 ; Ivii. p. 43.

^ Halliburton, Quart. Joitrn. Micr. Sc, London, July 18S5.



THE FATS.



17



in Fig. 5. For many years it was regarded as a carljohydrate, though an

exceptional one. It is sweet to the taste, but it gives none of the

characteristic reactions of sugar. As the chemical constitution of the

sugars was revealed, it became more and more evident that inosite is

not a sugar. Its constitution was

worked out by Maquenne^ from a

study of its nitro-substitution and

other products. It belongs to the

substances which have a closed

carbon chain, and its graphic formula

may be written thus : —

CHOH



CHOH



CHOHl



CHOH



CHOH




CHOH



Fig. 5. — Inosite crystals. — After Frey.



The Fats.

Fat is found in most of the animal tissues. The following table from
Gorup-Besanez gives the percentage in the organs and fluids of the body: —



Sweat .


0-001


Cartilage


1-3


Vitreous humour


0002


Bone .


1-4


Saliva .


0-02


Crystalline lens .


2-0


Lymph .


0-05


Liver .


2-4


Synovia


0-06


Muscles


3-3


Liquor amnii


0-06


Hair .


4-2


Chyle .


0-2


Brain .


8-0


Mucus .


0-3


Egg . . . ■


11-6


Blood .


0-4


]S[erves


22-1


Bile .


1-4


Adipose tissue


82-7


Milk .


4-3


Marrow


96-0



The fats are usually extracted from the finely divided tissue by
means of ether in a Soxhlet's apparatus, but in the case of many organs
the extraction is incomplete. Dormeyer therefore recommends that
the tissue should be subjected to artificial gastric digestion before the
extraction with ether ; "^ when this was done, flesh was found to yield an



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