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soluble in alkalis, but precipitable from such solution by acetic acid.
On boiling with dilute mineral acid they yield a substance which
reduces Fehling's solution. They are found in the secretion of mucous
glands, including the mucous salivary glands, and of slimy animals like

^ For the principal papers on alkaloidal substances in urine, see Baumann and
Udranszky, Ztsclir. f. physioL. Chem., Strassburg, Bd. xiii. S. 562 ; Stadthagen and Brieger,
Virchow'n Archiv, Bd. cxv. ; Stadthagen, Ztschr. f. klin. Med., Berlin, 1889, Bd. xv. Heite
5 and 6 ; Pouchet, Compt. rend. Acad. d. sc, Paris, tome xcviii. p. 1360 ; Bouchard, ibid.,
tome cii. pp. 669, 727, 1127 ; Griffiths, ibid., tomes cxiii., cxiv. , and cxv. ; Gautier, Btill.
Acad, de med., Paris, 1886, tome xix. A very complete bibliography will be found in
Huppert-Neubauer's "Analyse des Harns," 9th edition, p. 241.

- Quatretages, see Ganigee, "Physiological Chemistry," vol. i. p. 131; Krukenberg,
"Vergl. physiol. Studien," 2te Reihe. Abth. 1, S. 87; Lankester, Journ. Anat. and
Physiol., London, vol. ii. p. 114 ; vol. iii. p. 119. ; MacMunu, Quart. Journ. Micr. Sc,
London, Oct. 1885.

^ Fredericq, Bull. Acad. roy. de med. de Belg., Bruxelles, 1878, Ser. 2, tome xlvi. No.
11 ; Halliburton, Journ. Physiol., Cambridge and London, vol. vi. p. 300. In the latter
paper numerous references to other writers will be found.

■* A. H. Church, Proc. Boy. Soc. London, 1869, vol. xvii. p. 436 ; Phil. Trans., London,
1869, vol. clix. p. 627 ; 1892, vol. clxxxiii. p. 511 ; A. Gamgee, Proc. Roy. Soc. London,
1896, vol. lix. p. 339.


snails.^ A mucinogen is found in the investment around frogs' eggs ; ^
it is also the most important constituent of the intercelhilar or ground
substance of connective tissues, and has been especially investigated
in the jelly-like connective tissues (vitreous humour,=^ Whartonian
jelly * ), and in tendon.^

Elementary analysis of different mucins has given different results, as Avill
be seen from the following table : —

Snail Mucin.



Submaxillary Mucin.



Chittenden. 8


c .






H .






N .






S .











The mucins thus contain less carbon, and considerably less nitrogen,
than proteids.

Decomposition j^roducts of mucin. — By the action of superheated
steam, a carbohydrate is split off from mucin, which was called animal
gum by Landwehr.^^ He assigns to it the formula (CgHjuOr,). By
the action of dilute mineral acids this is converted into a reducing but
non-fermentable sugar or gummose {GJl^<f)^. The gmn-like substance
obtained from submaxillary mucin contains nitrogen.^^ The sugar
obtained from tendon mucin by Chittenden yielded an osazone melting
at 160°, and resembled that obtained from pentoses. F. Mliller^^has
investigated the mucin of sputum. He found it yielded as much as
25 to 32 per cent, of a reducing substance ; this is not a pentose, but is
probably glucosamine.

1 Eichwald, Ann. d. Ckem., Leipzig, Bd. cxxxiv.

" Giacosa, Ztschr. f. iihysiol. Chem., Strassburg, Bd. vii. S. 40; Hamniarsten, Arch. f.
d. ges. Physiol., Bonn, Bd. xxxvi. ; Wolfenden, Journ. Physiol., Cambridge and London,
voL V. p. 91.

2 K. A. Young, Journ. Physiol., Cambridge and London, 1894, vol. xvi. p. 325 ; C. Th.
Morner, Ztschr. f. physiol. Chem., Strassburg, 1893, Bd. xviii. S. 245. References to previous
literature will be found in these papers. Young arrived at the conclusion that the principal
substance in vitreous humour is mucinogen, not mucin.

^ Jernstrom, Jahresb. ii. d. Fortschr. d. Thier-Chem., Wiesbaden, 1889, Bd. x. S. 34.
Y''oung, loc. cit., sejjarated two mucins from the Whartonian jelly, one soluble, the other
insoluble in excess of acetic acid.

* Rollett, Sitznngsb. d. Ic. Akad. d. Wisscnsch., Wien, Bd. xxxix. S. 308, Strieker's
"Handbuch," Bd. i. S. 72. Loebisch, Ztschr. f. j^hysiol. C'/tem., Strassburg, Bd. x. S. 40 ;
Chittenden and Gies, Journ. ExjJer. Med., Baltimore, 1896, vol. i. p. 188.

® Arch. f. cl. ges. Physiol., Bonn, Bd. xxxvi. "' Loc. cit.

8 Loc. cit. Tlie high percentage of sulphur found is attributed by Chittenden to proteid

" Ztschr. f. jihysiol. Cheiii., Strassburg, Bd. xii.

'^^ Arch. f. d. ges. Physiol., Bonn, Bd. iv. S. 336. Probably Obolensky's preparation
was not so pure as Hammarsten's.

" Ztschr. f. 2)hysiol. Chem., Strassburg, 1881, Bd. viii. S. 124, 199 ; Arch. f. d. ges.
Physiol., Bonn, Bde. xxxix. and xl.

^^ Hammarsten, " Physiol. Chem.," 3rd German edition, p. 39.

13 Centralbl. f. Physiol., Leipzig, 1896, Bd. x. S. 480; Sitzungsb. d. Gesellsch. z. Beford.
d. ges. Naturw. zu Marburg, 1896, No. 6.


By the action of dilute mineral acids on mucin, this reducing sub-
stance, whatever its exact nature is, is also olitained, together with syntonin
and proteose-like materials, from the proteid part of the mucin molecule.
Strong acids lead to the formation of leucine, tyrosine, and levulmic acid
(Landwehr). Strong alkalis lead to the formation of similar products ;
but weak alkalis, like lime water, have no effect on tendon mucin, though
they readily break up sulmiaxillary mucin (Loebisch). There is a good
deal of difference among the mucins in their soluljilities in acid and
alkaline solutions. Obolensky obtained pyrocatechin Ijy Ijoihng sub-
maxillary mucin with caustic soda ; but I have not succeeded in getting
it from connective tissue mucin.^

The putrefactive products of mucin are similar to those obtained
from proteids.

Mucoids or mucinoids. — These are mucin-like substances, which differ
from the true mucins either in being non-precipitable from alkahne solu-
tions by acetic acid, or in being readily soluble in excess of acetic acid. The
designation was originally given to this class by Hammarsten, and includes
the following substances : —

1. The mucin from vitreous humour.

2. The mucin from cartilage — chondro-mucoid (see "Cartilage").

3. The mucin from cornea — cornea-mucoid.^

4. Pseudo-mucin ; the colloid-like substance often found in ovarian fluids,
and previously known as paralbumin and metalbumin.'^

5. A similar mucoid, sometimes found in ascitic fluid.'*

6. Ovomucoid, a miicoid found in white of egg. This was first studied
by K'eumeister,^ who called it pseudo-peptone, then by Salkowski,'' and finally
by C. T. Morner,'^ who identified it as a mucoid.

7. Paramucin, a substance found sometimes in ovarian cysts, diflering
from pseudomucin in reducing Fehling's solution Avithout previous treatment
with acids (K. MitjukofF).^ Leatlies,^ who has worked at this substance under
Drechsel's supervision, finds that the reducing substance yields no osazone ;
that on decomposition it yields sulphuric acid, and thus resembles chondro-
mucoid; and on treatment with hydrochloric acid it gives off carbonic anhydride.
Its nature is still uncertain.

Hycdogens. — The term hyalin was originally applied to the principal
constituent of the waff of hydatid cysts.^" Krukenbergi^ extended the
name to allied substances obtainable from other animal structures. In the
natural state these substances are insoluble, and are termed hyalogens ; by the
action of alkalis or superheated water they are converted into the sohdole
hyalins. Neossidin is the hyalin obtained from neossin,i- the chief con-
stituent of the edible bird's nest. Chondrosidin and chondrosin are the hyalin
and hyalogen respectively obtained from the sponge, Chondrosia reniformis,

^ See also Young, loc. cit.

- G. T. Morner, Ztschr. f. pliysiol. Chcin., Strassburg, Bd. xviii. S. 213.

^ Hammarsten, '^Lehrbuch d. iihysiol. Chem.," .3i-d German edition, S. 366. See also
Hammarsten, Jahresb. ii. d. Fortsclir. d. Thicr-Ghem., Wiesbaden, Bd. xi. S. 11 ; Land-
wehr, Ztschr. f. 2yhysiol. Chem., Strassburg, Bd. vii. S. 118.

•* Hammarsten, iUd., 1891, Bd. xv. S. 202.

5 Ztschr. f. Biol., Miinchen, Bd. xxvii. S. 309.

" CentralU. f. d. vied. IFissensch. , Berlin, 1893, Nos. 31 and 43.

'' Ztschr./. j)hysiol. Chem., Strassburg, Bd. xviii. S. 525.

* Inaug. Diss., Berlin, 1895.

** Gommunication to Physiological Society, London, Oct. 17, 1896 -(not published).

" Liicke, Firchours Archiv, Bd. xix. S. 189.

" Ztschr./. Biol., Mtinchen, Bd. xxii. S. 261.

1^ The word "neossin" is Mulder's, Bull, des sc. phys. in Kedcrlande, 1838, S. 172;
Green, Joimi. Physiol., Gambridge and London, vol. vi. p. 40, pointed out the resemblance
of the nest substance to mucin.


spirographidin and spirographin from the skeletal tissues of the worm Spiro-
graphis. Krukenberg obtained a hyalogen also from the tubes of Onuphis
tuhicola, another from the membrane of Descemet and lens capsule (membranin,
C. T. Morner)/ and another from hyaline cartilage (now called chondroitin-
sulphuric acid, see " Cartilage "). These substances are all, like the mucins and
mucoids, decomposed by acids with the formation of a reducing substance.
They differ from the mucins in some of their solubilities, but it is doubtful
whether they should be classed apart from the mucoids.

Phosplio-gluco-profeids. — These substances not only yield a reducing
carbohydrate or carbohydrate-like body, like the mucins and mucoids, but on
gastric digestion they leave a residue of pseudo-nuclein, a substance which,
like nuclein, contains phosphorus. Pseudo-nuclein does not, however, yield
bodies of the xanthine group, on further decomposition, as do true nucleins.
Among these substances are the following : —

(a) IcMlmlin, a substance separated from the eggs of the carp by Walter,'-^
and at first supposed to be identical Avitli vitellin.

{h) Helico-proteid., secreted by the glands of the snail {Helix pomatia), and
separated by Hammarsten.^ By the action of alkalis a levorotatory carbohydrate
(animal sinistrin) is split off ; a dextrorotatory reducing sugar is obtained by the
use of dilute mineral acids.

(c) The principal constituent of the cells of the pancreas is a complex
nucleo-proteid which Hammarsten* considers to be identical with trypsin ;
by boiling this, it is split into coagulated proteid and a phospho-gluco-j)roteid.
The sugar which this substance gives, on treatment with dilute acids, is
probably a pentose (see p. 3).

Kossel and his pupils have also obtained reducing sugar-like substances
from yeast nuclein.

In concluding the subject of the gluco-proteids, it may again be mentioned
that Pavy regards all the common proteids (casein excepted) as having a
glucoside constitution (see p. 30). Whether this be so or not, the fact insisted
upon by Pavy that a carbohydrate may be obtained by hydrolytic decompo-
sition of proteids has been confirmed by other observers. Thus K. Morner
obtained from serum globulin a reducing substance on treatment with
hydrochloric acid, which, like Pavy's, is optically inactive ; but failed to get
such a substance from purified myosin, vitellin, crystallin, serum albumin, and
egg albumin. He got it from fibrin, but considered that it was due to carbo-
hydrate in entangled blood corpuscles.^ I myself was at one time of opinion
that Pavy's results, which were principally obtained with egg-white, were due
to the admixture of the pure albumin with a mucoid (ovomucoid, Avhich
exists to the extent of 10 per cent, in egg-white); but I learn from Dr. Pavy
that his method of preparing coagulated egg-white would exclude any large
admixture of this kind. Pavy's work, moreover, has been recently confirmed
by N. Krawkow.'^ He found egg-white difficult to obtain free from ovomucoid,
but the purest products he obtained always yielded a reducing substance,
which gave a crystalline osazone (melting at 183° to 185° C. ; Pavy gives
189° C). This reducing substance he regards as a carbohydrate, though he
does not commit himself as to its identity. He, however, never found pen-
toses, nor did he find that the gastric digestion of egg albumin yielded any
carbohydrate. The same carbohydrate was obtained from acid albumin,
alkali albumin, albumose, peptone, fibrin, serum albumin, serum globulin,
and lact-albumin. Casein, vitellin, gelatin, and nucleo-proteid from peas
gave a negative result. Albumin from peas yielded an osazone rather

1 Ztschr. f. phyaiol. Clicm., Strassburg, Bd. xviii. S. 213. ^ Ibid. Bd. xv.

•^ Arch.f. d. ges. Physiol., Bonn, Bd. xxxvi.

'^ Ztschr. f. pliysiol. Chem., Strassburg, Bd. xix. S. 19.

5 Gcntralhl. f. Physiol., Leipzig, Bd. vii. S. 581.

6 Arch.f. d. ges. Physiol., Bonn, 1896, Bd. Ixv. S. 281.


different in its characters from the one just described. H. Weydemann^ has
also confirmed Pavy's work ; he considers that the material in the proteid
that yields the reducing substance is identical with Landwehr's animal gum.

The nucleins. — Lauder Brunton ^ described the nuclei of the red
corpuscles of birds as consisting of a mucin-like substance. Plosz,^
however, found that, though the marterial in question resembled mucin
in its solubility in alkalis, and precipitability by acids, it was not mucin,
as it contains a high percentage of phosphorus. About the same time
Miescher * separated a similar phosphorus-rich substance from the nuclei
of pus corpuscles ; the pus was subjected to gastric digestion, and the
nuclein alone remained undissolved. Later, Miescher ^ prepared a similar
substance from the spermatozoa of different animals, and from egg-yolk ;
Hoppe-Seyler,^ Kossel,'' and Loew^ from yeast, Plosz^ from the liver,
Jaksch^*' and Geoghegan^^ from brain, Lubavin ^^ from cows' milk, and
Worm-Miiller ^^ from egg-yolk.

It was soon surmised that nuclein is not a single substance, because
the different nucleins vary in their solubilities, and even in their compo-
sition. Miescher's nuclein from spermatozoa, for instance, contained no
sulphur. Of recent years our knowledge of the nucleins has been con-
siderably advanced by Kossel,^"^ Liebermann, and others.

It has long been known that metaphosphoric acid is a precipitant
of albumin. Liebermann ^^ examined this precipitate and found that it
gave many of the reactions of nuclein. He therefore came to the con-
clusion that nuclein is simply a compound of albumin with phosphoric
acid. Malfatti ^^ carried this idea still further, for he found that, by
fractional precipitation with different amounts of phosphoric acid, he
was able to obtain a chain of nucleins with different amounts of
phosphorus in each, and with varying solubilities, corresponding closely
with those obtainable from nuclei.

Pohl,^'^ however, very soon showed that Liebermann's precipitate
differs from true nuclein {i.e. the nuclein from nuclei) in the fact that
substances of the xanthine group are not obtainable from it on
decomposition, and KosseP^ has contested Liebermann's and Malfatti's
views chiefly on the same grounds.

Kossel divides the nucleins into two groups. The first is that of
the true nucleins. These are obtainable from nuclei; they yield on
decomposition the xanthine bases — hypoxanthine, adenine, and other sub-
stances of the same group. The second class of nucleins may be called
pseudo-nucleins, and include those obtainable from milk, egg-yolk,

1 Inaug. Diss., Marburg, 1896 ; Centralhl. f. Physiol., Leipzig, 1897, Bd. x. S. 749.

- Journ. Anat. and Physiol., London, 2nd series, voL iii. p. 91.

3 Hoppe-Seyler, "Med." Ghem. Untersuch. , " 1871, Heft 4, S. 460. * Ibid., S. 441.

^ Verhandl. d. nalurf. Gesellsch. in Basel, 1874, Heft i.

s "Med. Cheni. Untersuch.," Bd. iv. S. 500.

'' Ztschr. f. physiol. Chem. , Strassburg, Bde. iii. and iv.

8 Arch.f. d. ges. Physiol., Bonn, 1880, Bd. xxii. ^ Ibid., Bd. vii.

^° Ibid., Bd. xiii, ^^ Ztschr. f. physiol. Chem., Strassburg, Bd. i.

^- Per. d. deutsch. chem. Gesellsch., Berlin, Bd. x. S. 2237.
13 Arch.f. cl. ges. Physiol., Bonn, 1873, Bd. viii. S. 190.

•'■* Ztschr. f. physiol. Chem., Strassburg. Numerous papers from Bd. viii. to present time.
1^ Ber. d. deutsch. chem. Gesellsch. , Berlin, Bd. xxi. S. 598.

^^ Ber. d. naturw.-mcd. Ver. in Innsbruck, 1891-92, Bd. xx. ; Ztschr. f. physiol. Chem.,
Strassburg, Bd. xvi. S. 69 ; xvii. S. 8.

^"^ Ztschr. f. physiol. Chem., Strassburg, Bd. xiii. S. 292.

•■* Verhcmdl. d. physiol. Gesellsch., Berlin, Oct. 21, 1892 (in Arch. f. Physiol., Leipzig,

VOL. I.— 5


and Liebermann's artificial uucleiii. Altmann^ showed that the
nitrogenous bases just alluded to originate from a complex organic acid,
which he termed nucUic acid, and that the true nucleins differ from one
another in the relative quantities of proteid and nucleic acid which they
contain. Nucleic acid is free from sulphur, and is in fact identical with
Miescher's nuclein from spermatozoa. Miescher's formula for this
sulphur-free material was C29H4gNgP3022. Kossel's is CgoHaoNgPsOiy.
More recent investigations by Miesclier,^ which were not pul)lished
until quite recently (after his death), by Schmiedeberg, led him to adopt
the formula C4oH54]Sri^Oi7(P205).2 for nucleic acid. He further considered
that in the spermatozoa, this acid is united to protamine. An exami-
nation of a preparation of nucleic acid, made from yeast by Altmann,
showed that here the formula was C4oB[59]Sri6022(P205)2 (see further
under " Spermatozoa "). Nucleic acid does not give the proteid reactions.
The relative amount of nucleic acid in different nucleins can be roughly
determined by micro-chemical reactions with aniline dyes, nucleic acid
having a great affinity for basic dyes like methyl-green.^

Hoppe-Seyler's classification of nucleins is the following : —

1. Nucleins like those found in spermatozoa, which contain no proteid,
but consist only of nucleic acid.

2. The true nucleins, those found in cell nuclei. They yield proteid,
xanthine or alloxuric bases (hypoxanthine, xanthine, guanine, adenine),
and phosphoric acid. Those richest in nucleic acid occur in the chro-
matic fibres of the nucleus ; poorer in nucleic acid are the nucleins which
occur in the nucleoli {e.g. pyrenin), and which constitute the chief bulk
of the substance called plastin by histologists ; these are comparatively
insoluble in alkalis. They form numerous links in a chain which passes
insensibly into the group of the nucleo-proteids.

3. The para-nucleins (or pseudo-nucleins) ; these are the nucleins
obtainable from nucleo-proteids (caseinogen, vitellin, cell nucleo-proteids).
They yield (like Liebermann's artificial nuclein) no nitrogenous bases,
but only proteid and phosphoric acid on boiling with water or dilute
acid. The nucleo-proteids of cell protoplasm can only be provisionally
included in this group ; they contain so little nuclein, that even if
xanthine bases were obtained from these (and the point does not seem
to have been thoroughly investigated yet) the small yield might escape
detection. The nucleo-proteid from muscle yields some of these bases
(see " Chemistry of Muscle ").

There are at least four nucleic acids. They are compounds of an acid with
various bases, such as adenine, hypoxanthine, guanine, and xanthine. They
differ in the amount and character of the bases, and in the acid with
which these bases are combined. That from the thymus is cahed adenyhc
acid (from the fact that its chief base is adenine). This, when heated with
sulphuric acid, yields a crystalline substance called thymin"* (Cr,Hj3N.,0._,),
cytosine, ammonia, levulinic acid, formic acid, and phosphoric acid. The
yield of cytosine, a new crystalline base (C2iH,;f,N;^j304-(- SH.^O) amounts to
about 2 per cent, of the nucleic acid employed. The presence of levul-
inic acid among the products of decomposition is significant, and shows
that adenylic acid contains a carbohydrate group. This agrees with previous

^ Arch. f. Physiol., Leijmg, 1889, S. 524. See also Kossel, ibid., 1891.
" Arch. f. ex'pcr. Fatli. u. PliannakoL, Leipzig, 1896, Bd. xxxvii. S. 100.
3 For a criticism of these niiorochemical methods, see Heine, Ztschr. f. 2}hysiol. Cliem.f
Strassburg, Bd. xxi. S. 494.

■* Kossel and Neumann, Ber. d. dcutsch. chem. Gescllsch., Berlin, Bd. xxvi. S. 2753.


researches of Kossel, who obtained a carbohydrate from the nucleic acid of
yeast. ^

Kossel and N'eumann '■^ have further shown that adenylic acid yields also
a new acid called thymic acid, precipitable as a barium salt (C,i;H.,.,N.,Pr,0^.,Ba).
The acid is readily soluljle in cold water, and differs from nucleic acid in not
being precipitated by mineral acids.-'^

Eesearches such as these show how complicated the subject is, and
how much yet remains to be discovered, especially regarding the nuclein
acids. The nuclein bases are comparatively simple, and the principal
ones may be arranged in two groups : — •

Adenine has the formula C5H5N5 ; on heating it with sulphuric acid,
jSTH is replaced by 0, and liypoxanthine is formed : —

(adenine) (water) (liypoxanthine) (ammonia)

Both substances contain a radicle, C5H4N4, which Kossel terms adenyl ;
adenine is its imide, liypoxanthine its oxide. The following equation
shows a similar relationship between guanine and xanthine : —

C5H4N4O.NH + H,0 = C5H4N4O2 + NH3

(guanine) (water) (xanthine) (ammonia)

On comparing the formulae of hypoxanthine and xanthine with uric
acid (C5H4N4O3), we see their close relationship. Leaving aside other
possible ways in which uric acid is undoubtedly formed in the organism,
we have here a way in which uric acid may arise by oxidation
from the nuclein bases, and thus ultimately from the nuclei of cells.*
The name " alloxviric bases " for these substances was suggested by
Kriiger and Wulff.^ They are often spoken of as the " xanthine bases."

The nucleo-proteids. — These are compounds of nuclem with pro-
teids. The amount of proteid matter is large, and the substances in
question give the reactions of proteids, and in theu' solubilities approach
very nearly to the globulins. On gastric digestion the nuclein they con-
tain is left as an insoluble residue, but on pancreatic digestion a good
deal of the nuclein is dissolved, and presumably, when this occurs in the
body, is absorbed.^

Hammarsten divides the nucleo -proteids into two classes ; the first, to
which he restricts that name, yields true nuclein on gastric digestion ;
the other class he calls nucleo-albumins ; these yield pseudo-nuclein on
gastric digestion, and include caseinogen and vitellin. In addition to
these, there are the phospho-gluco-proteids, which have already been
described (p. 64).

Nucleo-proteids, using the term in the widest sense, are obtain-

1 Kossel and Neumann, £er. d. deutsch. cJiem. Gesellsch., Berlin, Bd. xxvii. S. 2215.

-Ztschr. f. 'physiol. Chem., Strassburg, Bd. xxii. S. 74.

" It was later obtained from spermatozoa nuclein (Kossel, ibid., p. 188). Milroy (ibid.,
1896, Bd. xxii. S. 307) states that the precipitate formed on adding nucleic acid to a solu-
tion of albumin resembles true nuclein in its characters ; whereas the precipitate produced
by thyinic acid is somewhat similar to para-nuclein or pseudo-nuclein.

'^ This subject has been specially taken up by Horbaczewski {Sitzungsb. d. k. Akad. d.
JFissensch., Wien, Bd. c. ), who has pointed out the close relationship between uric acid
formation and leucocytosis. Diet increases uric acid formation by leading to an increase
of leucocytes, or possibly, as some recent investigators think, the increase is chiefly due
to the nuclein in the food (Weintrand, Chem. Centr.-BL, Leipzig, 1895, Bd. ii. S. 54,
234, 310). See also Umber, Ztschr. f. klin. Med., Berlin, 1896, Bd. xxix. S. 174 ; Camerer,
Ztschr.f. Biol., Miinchen, 1896, Bd. xxxiii. S. 139.

^ Ztschr. f. physiol. Chem., Strassburg, 1894, Bd. xx. S. 176.

^ Popoff, Ztschr.f. 2-)hysiol. Chem., Strassburg, Bd. xviii. S. 533 ; Gumlich, ibid., S. 508.


able from the nuclei and protoplasm of cells. They appear to lie the
most abundant of the proteid materials obtainable from cells. Nucleo-
histon is the name of one of these separated from the thymus by Kossel
and Lilienfeld.^ The latter gives its percentage composition as
C, 48-46; H, 7; ^^ 16-86; P, 3-025; S, 0-7; 0, 23-95. The high
percentage of phosphorus given here has never been obtained by me,
from the numerous nucleo-proteids I have prepared and examined from

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