CONSTITUENTS OF FUNGI
VERSUCHE ZUR BESTIMMUNG DES GEHALTS EINIGER PFLANZEN UND PFLANZENTEILE
AN ZELLWANDBESTANDTEILEN AN HEMICELLULOSEN UND AN CELLULOSE.
A. KLEIBER (Landw. Vers.-Stat., 1900, 54, 161).
~ON THE DETERMINATION OF CELL-WALL CONSTITUENTS, HEMICELLULOSES AND
CELLULOSE IN PLANTS AND PLANT TISSUES.~
In a preliminary discussion the author critically compares the results
of various of the methods in practice for the isolation and estimation
of cellulose. The method of F. Schulze [digestion with dil. HNO_{3} with
KClO_{3}--14 days, and afterwards treating the product with ammonia,
&c.] is stated to be the 'best known' (presumably the most widely
practised); W. Hoffmeister's modification of the above, in which the
nitric acid is replaced by hydrochloric acid (10 p.ct. HCl) is next
noted as reducing the time of digestion from 14 days to 1-2 days, and
giving in many cases higher yields of cellulose. The methods of treating
with the halogens, viz. bromine water (H. Mueller), chlorine gas (Cross
and Bevan), and chlorine water, are dismissed with a bare mention,
apparently on the basis of the conclusions of Suringar and Tollens
(_q.v._). The method of Lange, the basis of which is a 'fusion' with
alkaline hydrates at 180 deg., and the modified method of Gabriel, in which
the 'fusion' with alkali takes place in presence of glycerin, are
favourably mentioned.
These methods were applied to a range of widely different raw materials
to determine, by critical examination of the products, both as regards
yield and composition, what title these latter have to be regarded as
'pure cellulose.'
This portion of the investigation is an extension of that of Suringar
and Tollens, these latter confining themselves to celluloses of the
'normal' groups, i.e. textile and paper-making celluloses. The present
communication is a study of the tissue and cell-wall constituents of the
following types:--
1. Green plants of false oat grass (_Arrhenatherium, E._).
2. Green plants of lucerne (_Medicago sativa_).
3. Leaves of the ash (_Fraxinus_).
4. Leaves of the walnut (_Juglans_).
5. Roots of the purple melic grass (_Molinia caerulea_).
6. Roots of dandelion (_Taraxacum officinale_).
7. Roots of comfrey.
8. Coffee berries.
9. Wheat bran.
These raw materials were treated for the quantitative estimation of
cellulose by the method of Lange (b), Hoffmeister (c), and Schulze
(d), and the numbers obtained are referred for comparison to the
corresponding yields of 'crude fibre' (Rohfaser) by the standard method
(a).
As a first result the author dismisses Lange's method as hopeless: the
results in successive determinations on the same materials showing
variations up to 60 p.ct. The results by c and d are satisfactorily
concordant: the yields of cellulose are higher than of 'crude fibre.'
This is obviously due to the conservation of 'hemicellulose' products,
which are hydrolysed and dissolved in the treatments for 'crude fibre'
estimation. A modified method was next investigated, in which the
process of digestion with acid chloroxy- compounds (c and d) was
preceded by a treatment with boiling dilute acid. The yields of
cellulose by this method (e) are more uniform, and show less
divergence from the numbers for 'crude fibre.'
The author's numerical results are given in a series of tables which
include determinations of proteids and ash constituents, and the
corresponding deductions from the crude weight in calculating to 'pure
cellulose.' The subjoined extract will illustrate these main lines of
investigation.
___________________________________________________________
| | | |
| | Crude Fibre | Pure Cellulose |
| |_____________|____________________________|
| | | | |
| Raw Material | Weende | Hoffmeister | Hoffmeister, |
| | Method. | Method. | modified by |
| | (a) | (c) | Author. |
| | | | (e) |
|________________|_____________|_____________|______________|
| | | | |
| Oat grass | 30.35 | 34.9 | 31.5 |
| Lucerne | 25.25 | 28.7 | 20.5 |
| Leaves of ash | 13.05 | 15.4 | 13.8 |
| Roots of melic | 21.60 | 29.1 | 21.4 |
| Coffee beans | 18.30 | 35.1 | 23.3 |
| Bran | 8.2 | 19.3 | 9.3 |
|________________|_____________|_____________|______________|
The final conclusion drawn from these results is that the method of
Hoffmeister yields a product containing variable proportions of
hemicelluloses. These are eliminated by boiling with a dilute acid (1.25
p.ct. H_{2}SO_{4}), which treatment may be carried out on the raw
material--i.e. before exposure to the acid chlorate, or on the crude
cellulose as ordinarily isolated.
~Determination of Tissue-constituents.~--By the regulated action of
certain solvents applied in succession, it appears that such
constituents of the plant-complex can be removed as have no organic
connection with the cellular skeleton: the residue from such treatments,
conversely, fairly represents the true tissue-constituents. The author
employs the method of digestion with cold dilute alkaline solutions
(0.15 to 0.5 p.ct. NaOH), followed by exhaustive washing with cold and
hot water, afterwards with cold and hot alcohol, and finally with ether.
The residue is dried and weighed as crude product. When necessary, the
proportions of ash and proteid constituents are determined and deducted
from the 'crude product' which, thus corrected, may be taken as
representing the 'carbohydrate' tissue constituents.
~Determination of Hemicelluloses.~--By the process of boiling with dilute
acids (1.25 p.ct. H_{2}SO_{4}) the hemicelluloses are attacked--i.e.
hydrolysed and dissolved. The action of the acid though selective is, of
course, not exclusively confined to these colloidal carbohydrates. The
proteid and mineral constituents are attacked more or less, and the
celluloses themselves are not entirely resistant to the action. The loss
due to the latter may be neglected, but in calculating the hemicellulose
constants from the gross loss the proteids and mineral constituents
require to be taken into account in the usual way.
QUANTITATIVE SEPARATION OF HEMICELLULOSE, CELLULOSE, AND LIGNIN.
PRESENCE OF PENTOSANES IN THESE SUBSTANCES.
WILHELM HOFFMEISTER (Landw. Versuchs-Stat, 1898, 50, 347-362).
(p. 88) The separation of the cellulose-like carbohydrates of sunflower
husks is described.
In order to ascertain the effect of dilute ammonia on the cellulose
substances of lignin, a dried 5 p.ct. caustic soda extract was extracted
successively with 1, 2, 3, and 4 p.ct. sodium hydroxide solution. Five
grams of the 2 p.ct. extract were then subjected to the action of
ammonia vapour; the cellulose did not completely dissolve in six weeks.
Cellulose insoluble in caustic soda (32 grms.) was next extracted with
ammonia, in a similar manner, for 10 days, dried, and weighed. 30.46
grms. remained, which, when treated with 5 p.ct. aqueous caustic soda,
yielded 0.96 grm. (3 per cent.) of hemicellulose.
When cellulose is dissolved in Schweizer's solution, the residue is, by
repeated extraction with aqueous sodium hydroxide, completely converted
into the soluble form. On evaporating the ammonia from the Schweizer's
extract, at the ordinary temperature and on a water-bath respectively,
different amounts of cellulose are obtained; more hemicellulose is
obtained, by caustic soda, from the heated solution than from that which
was not heated. In this operation the pentosanes are more influenced
than the hexosanes; pentosanes are not always readily dissolved by
caustic soda, and hexosanes are frequently more or less readily
dissolved. Both occur in lignin, and are then undoubtedly indigestible.
These points have to be considered in judging the digestibility of these
carbohydrates.
A comparison of analyses of clover, at different periods, in the first
and second years of growth, shows that both cellulose (Schweizer's
extract) and lignin increase in both constituents. In the second year
the lignin alone increased to the end; the cellulose decreased at the
end of June. In the first year it seemed an absolutely as well as
relatively greater amount of cellulose, and lignin was produced in the
second year; this, however, requires confirmation. The amount of
pentosanes in the Schweizer extract was relatively greater in the second
than in the first year, but decreased in the lignin more in the second
year than in the first: this result is also given with reserve.
DIE CONSTITUTION DER CELLULOSEN DER CEREALIEN.
C. F. CROSS, E. J. BEVAN, and C. SMITH (Berl. Ber., 1896, 1457).
~THE CONSTITUTION OF THE CEREAL CELLULOSES.~
(p. 84) Straw cellulose is resolved by two methods of acid hydrolysis
into a soluble furfural-yielding fraction, and an insoluble fraction
closely resembling the normal cellulose. (a) The cellulose is
dissolved in sulphuric acids of concentration, H_{2}SO_{4}.2H_{2}O,
H_{2}SO_{4}.3H_{2}O. As soon as solution is complete, the acid is
diluted. A precipitate of cellulose hydrate (60-70 p.ct.) is obtained,
and the filtered solution contains 90-95 p.ct. of the furfuroids of the
original cellulose. The process is difficult to control, however, in
mass, and to obtain the latter in larger quantity the cellulose (b) is
digested with six times its weight of 1 p.ct. H_{2}SO_{4} at 3 atm.
pressure, the products of the action being (1) a disintegrated cellulose
retaining only a small fraction (1/12) of the furfural-yielding groups,
and (2) a slightly coloured solution of the hydrolised furfuroids. An
investigation of the latter gave the following results: By oxidation
with nitric acid no saccharic acid was obtained; showing the absence of
dextrose. The numbers for cupric reduction were in excess of those
obtained with the hexoses. The yield of ozazone was high, viz. 30 to 40
p.ct. of the weight of the carbohydrate in solution. On fractionating,
the melting-points of the fractions were found to lie between 146 deg. and
153 deg.. Ultimate analysis gave numbers for C, H, and N identical with
those of a pentosazone. The product of hydrolysis appears, therefore, to
be xylose or a closely related derivative.
All attempts to obtain a crystallisation of xylose from the solution
neutralised (BaCO_{3}), filtered, and evaporated, failed. The reaction
with phloroglucol and HCl, moreover, was not the characteristic red of
the pentoses, but a deep violet. The product was then isolated as a dry
residue by evaporating further and drying at 105 deg.. Elementary analysis
gave the numbers C 44.2, 44.5, and H 6.7, 6.3. Determinations of
furfural gave 39.5 to 42.5 p.ct. On treating the original solution with
hydrogen peroxide, and warming, oxidation set in, with evolution of
CO_{2}. This was estimated (by absorption), giving numbers for CO_{2},
19.5, 20.5, 20.1 p.ct. of the substance.
The sum of these quantitative data is inconsistent with a pentose or
pentosane formula; it is more satisfactorily expressed by the empirical
formula
O
/ \
C_{5}H_{8}O_{3} CH_{2},
\ /
O
which represents a pentose monoformal. Attempts to synthesise a compound
of this formula have been so far without success.
UEBER EINIGE CHEMISCHE VORGAeNGE IN DER GERSTENPFLANZE.
C. F. CROSS, E. J. BEVAN, and C. SMITH (Berl. Ber., 1895, 2604).
~THE CHEMICAL LIFE-HISTORY OF THE BARLEY PLANT.~
(p. 84) Owing to the presence of 'furfuroids' in large proportion as
constituents of the tissues of the stems of cereals, these plants afford
convenient material for studying the problem of the constitution of the
tissue-furfuroids, as well as their relationship to the normal
celluloses. The growing barley plant was investigated at successive
periods of growth. Yield of furfural was estimated on the whole plant
and on the residue from a treatment with alkaline and acid solvents in
the cold such as to remove all cell contents. This residue is described
as 'permanent tissue.' The observations were carried out through two
growing seasons--1894-5--which were very different in character, the
former being rainy with low temperature, the latter being abnormal in
the opposite direction, i.e. minimum rainfall and maximum sunshine. The
barley selected for observation was that of two experimental plots of
the Royal Agricultural Society's farm, one (No. 1) remaining permanently
unmanured, and showing minimum yield, the other (No. 6) receiving such
fertilising treatment as to give maximum yields.
The numerical results are given in the annexed tables:
Table Headings:
A: Date
B: Age of Crop
C: Plot
D: Dry Weight
E: Furfural p.ct. of dry weight (a)
F: Permanent tissue p.ct. dry weight
G: Furfural from permanent tissue
H: P.ct. of tissue
I: P.ct. of entire plant
J: Ratio a : c
BARLEY CROP, WOBURN, 1894.
________________________________________________________________________
| | | | | | | | |
| | | | | | | [G] | |
| | | | | | |_____________| |
| | | | | | | | | |
| [A] | [B] | [C] | [D] | [E] | [F] | [H] | [I] | [J] |
|_________|__________|_____|______|______|______|______|______|__________|
| | | | | | | | | |
| May 7 | 6 weeks | 1 | 19.4 | 7.0 | 53.4 | 12.7 | 6.8 | 1.03 : 1 |
| | | 6 | 14.7 | 7.0 | 55.9 | 10.3 | 5.7 | 1.23 : 1 |
| June 4 | 10 weeks | 1 | 17.6 | 7.7 | 52.9 | 11.6 | 6.1 | 1.26 : 1 |
| | | 6 | 13.5 | 8.1 | 58.5 | 13.4 | 7.8 | 1.04 : 1 |
| July 10 | 15 weeks | 1 | 42.0 | 9.0 | 65.7 | 9.8 | 6.4 | 1.40 : 1 |
| | | 6 | 32.9 | 10.6 | 65.7 | 12.5 | 8.2 | 1.30 : 1 |
| Cut | 21 weeks | 1 | 64.0 | 11.9 | 70.0 | 14.5 | 10.1 | 1.18 : 1 |
| Aug. 21 | | 6 | 64.6 | 13.4 | 70.5 | 15.0 | 10.6 | 1.26 : 1 |
| Carried | 22 weeks | 1 | 84.0 | 12.7 | 75.0 | 16.5 | 12.4 | 1.02 : 1 |
| Aug. 31 | | 6 | 86.4 | 12.4 | 78.4 | 15.1 | 11.8 | 1.05 : 1 |
| |
| BARLEY CROP, WOBURN, 1895. |
| |
| May 15 | 7 weeks | 1 | 20.6 | 6.6 | 53.9 | 10.2 | 5.5 | 1.20 : 1 |
| | | 6 | 17.8 | 5.8 | 56.7 | 9.6 | 5.4 | 1.07 : 1 |
| June 18 | 12 weeks | 1 | 34.6 | 8.0 | 38.2 | 14.7 | 5.6 | 1.42 : 1 |
| | | 6 | 33.4 | 7.6 | 44.5 | 15.0 | 6.7 | 1.14 : 1 |
| July 16 | 16 weeks | 1 | 52.8 | 12.1 | 55.6 | 16.3 | 9.1 | 1.33 : 1 |
| | | 6 | 54.4 | 10.6 | 46.2 | 19.1 | 8.8 | 1.20 : 1 |
| Aug. 16 | 20 weeks | 1 | 66.8 | 9.2 | 49.1 | 17.0 | 8.3 | 1.10 : 1 |
| | | 6 | 65.0 | 9.8 | 49.8 | 19.1 | 9.4 | 1.04 : 1 |
| Sept. 3 | 22 weeks | 1 | 84.3 | 10.4 | 45.7 | 17.6 | 8.0 | 1.31 : 1 |
| | | 6 | 86.3 | 10.2 | 45.3 | 17.3 | 7.8 | 1.30 : 1 |
|_________|__________|_____|______|______|______|______|______|__________|
The variations exhibited by these numbers are significant. It is clear,
on the other hand, that the assimilation of the furfuroids does not vary
in any important way with variations in conditions of atmosphere and
soil nutrition. They are essentially _tissue_-constituents, and only at
the flowering period is there any accumulation of these compounds in the
alkali-soluble form. It has been previously shown (ibid. 27, 1061)
that the proportion of furfuroids in the straw-celluloses of the
paper-maker differs but little from that of the original straws. For the
isolation of the celluloses the straws are treated by a severe process
of alkaline hydrolysis, to which, therefore, the furfuroid groups offer
equal resistance with the normal hexose groups with which they are
associated in the complex.
The furfuroids of the cereal straws are therefore not pentosanes. They
are original products of assimilation, and not subject to secondary
changes after elaboration such as to alter either their constitution or
their relationship to the normal hexose groups of the tissue-complex.
(1) CONSTITUTION OF THE CEREAL CELLULOSES
(Chem. Soc. J. 1896, 804).
(2) THE CARBOHYDRATES OF BARLEY STRAW
(Chem. Soc. J. 1896, 1604).
(3) THE CARBOHYDRATES OF THE CEREAL
STRAWS (Chem. Soc. J. 1897, 1001).
(4) THE CARBOHYDRATES OF BARLEY STRAW
(Chem. Soc. J. 1898, 459).
C. F. CROSS, E. J. BEVAN, and CLAUD SMITH.
These are a series of investigations mainly devoted to establishing the
identity of the furfural-yielding group which is a characteristic
constituent.
This 'furfuroid' while equally resistant to alkalis as the normal
cellulose group with which it is associated, is selectively hydrolysed
by acids. Thus straw cellulose dissolves in sulphuric acids of
concentration H_{2}SO_{4}.2H_{2}O - H_{2}SO_{4}.3H_{2}O, and on diluting
the normal cellulose is precipitated as a hydrate, and the furfuroid
remains in solution. But this sharp separation is difficult to control
in mass. By heating with a very dilute acid (1 p.ct. H_{2}SO_{4}) the
conditions are more easily controlled, the most satisfactory results
being obtained with 15 mins. heating at 3 atm. pressure.
(1) Operating in this way upon brewers' grains the furfuroid was
obtainable as the chief constituent of a solution for which the
following experimental numbers were determined:--Total dissolved solids,
28.0 p.ct. of original 'grains'; furfural, 39.5 p.ct. of total dissolved
solids, as compared with 12.5 p.ct. of total original grains; cupric
reduction (calc. to total solids), 110 (dextrose = 100) osazone; yield
in 3 p.ct. solution, 35 p.ct. of weight of total solids.
Pentosazone
Analysis N 17.1 17.3 17.07
C 62.5 62.3 62.2
H 6.4 6.5 6.1
Melting-point 146 deg.-153 deg.
From these numbers it is seen that of the total furfuroids of the
original 'grains' 84 p.ct. are thus obtained in solution in the fully
hydrolysed form, which is that of a pentose or pentose derivative. It
was, however, found impossible to obtain any crystallisation from the
neutralised (BaCO_{3}) and concentrated solution, the syrup being kept
for some weeks in a desiccator. It was noted at the same time that the
colour reaction of the original solution with phloroglucol and
hydrochloric acid was a deep violet, in contradistinction to the
characteristic red of the pentoses. On oxidation with hydrogen peroxide,
in the proportion of 1 mol. H_{2}O_{2} to 1 mol. of the carbohydrate in
solution, carbonic anhydride was formed in quantity = 20.0 p.ct. of the
latter.
Fermentation (yeast) experiments also showed a divergence from the
resistant behaviour of the pentoses, a considerable proportion of the
furfuroid disappearing in a normal fermentation.
(2) The quantitative methods above described were employed in
investigating the barley plant at different stages of its growth. The
green plant was extracted with alcohol, the residue freed from alcohol
and subjected to acid hydrolysis.
The hydrolysed extract was neutralised and fermented. In the early
stages of growth the furfuroids were completely fermented, i.e.
disappeared in the fermentation. In the later stages this proportion
fell to 50 p.ct. In the earlier stages, moreover, the normal hexose
constituents of the permanent tissue were hydrolysed in large proportion
by the acid, whereas in the matured straw the hydrolysis is chiefly
confined to the furfuroids. In the early stages also the permanent
tissue yields an extract with relatively low cupric reduction, showing
that the carbohydrates are dissolved by the acid in a more complex
molecular condition.
These observations confirm the view that the furfuroids take origin in a
hexose-pentose series of transformations. The proportion of furfuroid
groups to total carbohydrates varies but little, viz. from 1/3 in the
early stages to a maximum of 1/4 at the flowering period. At this period
the differentiation of the groups begins to be marked.
Taking all the facts of (1) and (2), they are not inconsistent with the
hypothesis of an internal transformation of a hexose to a
pentose-monoformal. Such a change of position and function of oxygen
from OH to CO within the group --CH.OH-- is a species of internal
oxidation which reverses the reduction of formaldehyde groups in
synthesising to sugars, and appears therefore of probable occurrence.
These constitutional problems are followed up in (3) by the indirect
method of differentiating the relationships of these furfuroids to yeast
fermentation, from those of the pentoses. Straw and esparto celluloses
are subjected to the processes of acid hydrolysis, and the neutralised
extracts fermented. With high furfural numbers indicating that the
furfuroids are the chief constituents of the extract, there is an active
fermentation with production of alcohol. The cupric reduction falls in
greater ratio to the original (unfermented) than the furfural.
Observations on the pure pentoses--xylose and arabinose added to
dextrose solutions, and then exposed to yeast action--show that in a
vigorous fermentation not unduly prolonged the pentoses are unaffected,
but that they do come within the influence of the yeast-cell when the
latter is in a less vigorous condition, and when the hexoses are not
present in relatively large proportion.
(4) The observations on the growing plant were resumed with the view of
artificially increasing the differentiation of the two main groups of
carbohydrates. From a portion of a barley crop the inflorescence was
removed as soon as it appeared. The crop was allowed to mature, and a
full comparison instituted between the products of normal and abnormal
growth. With a considerable difference in 'permanent tissue' (13 p.ct.
less) and a still greater defect in cellulose (24 p.ct.), the constants
for the furfuroids in relation to total carbohydrates were unaffected by
the arrested development. This was also true of the behaviour of the
hydrolysed extracts (acid processes) to yeast fermentation.
(5) The extract obtained from the brewers' grains by the process
described in (2) was investigated in relation to animal digestion. It
has been now generally established that the furfuroids as constituents
of fodder plants are digested and assimilated in large proportion in
passing through animal digestive tracts, and in this respect behave
differently from the pentoses. The furfuroids being obtained, as
described, in a fully hydrolysed condition (monoses) the digestion
problem presented itself in a new aspect, and was therefore attacked.
The result of the comparative feeding experiments upon rabbits was to
show that in this previously hydrolysed form the furfuroids are almost
entirely digested and assimilated, no pentoses, moreover, appearing in
the urine.
Generally we may sum up the present solution of the problem of the
relationship of the furfuroids to plant assimilation and growth as
follows:--The pentoses are not produced as such in the process of
assimilation; but furfural-yielding carbohydrates are produced directly
and in approximately constant ratio to the total carbohydrates; they are
mainly located in the permanent tissue; in the secondary changes of
dehydration, &c., accompanying maturation they undergo such
differentiation that they become readily separable by processes of acid
hydrolysis from the more resistant normal celluloses; but in relation to
alkaline treatments they maintain their intimate union with the latter.
They are finally converted into pentoses by artificial treatments, and
into pentosanes in the plant, with loss of 1 C atom in an oxidised form.
The mechanism of this transformation of hexoses into pentoses is not
cleared up. It is independent of external conditions, e.g.
fertilisation and atmospheric oxidations, and is probably therefore a
process of internal rearrangement of the character of an oxidation.
ZUR KENNTNISS DER IN DEN MEMBRANEN DER PILZE ENTHALTENEN BESTANDTHEILE.
E. WINTERSTEIN (Ztschr. Physiol. Chem., 1894, 521; 1895, 134).
~ON THE CONSTITUENTS OF THE TISSUE OF FUNGI.~
(p. 87) These two communications are a contribution of fundamental
importance, and may be regarded as placing the question of the
composition of the celluloses of these lowest types on a basis of
well-defined fact. In the first place the author gives an exhaustive
bibliography, beginning with the researches of Braconnot (1811), who
regarded the cellular tissue of these organisms as a specialised
substance, which he termed 'fungin.' Payen rejects this view, and
regards the tissue, fully purified by the action of solvents, as a
cellulose (C_{6}H_{10}O_{5}). This view is successively supported by
Fromberg [Mulder, Allg. Phys. Chem., Braunschweig, 1851], Schlossberger
and Doepping [Annalen, 52, 106], and Kaiser. De Bary, on a review of the
evidence, adopts this view, but, as the purified substance fails to give
the characteristic colour-reactions with iodine, he uses the qualifying
term 'pilzcellulose' [Morph. u. Biol. d. Pilze u. Flechten, Leipzig,
1884].
C. Richter, on the other hand, shows that these reactions are merely a
question of methods of purification or preparation [Sitzungsber. Acad.
Wien, 82, 1, 494], and considers that the tissue-substance is an
ordinary cellulose, with the ordinary reactions masked by the presence
of impurities. In regard to the lower types of fungoid growth, such as
yeast, the results of investigators are more at variance. The researches
of Salkowski (p. 113) leave little doubt, however, that the
cell-membrane is of the cellulosic type.
The author's researches extend over a typical range of products obtained
from _Boletus edulis, Agaricus campestris, Cantharellus cibarius,
Morchella esculenta, Polyporus officinalis, Penicillium glaucum_, and
certain undetermined species. The method of purification consisted
mainly in (a) exhaustive treatments with ether and boiling alcohol,
(b) digestion with alkaline hydrate (1-2 p.ct. NaOH) in the cold,
(c) acid hydrolysis (2-3 p.ct. H_{2}SO_{4}) at 95 deg.-100 deg., followed by a
chloroxidation treatment by the processes of Schulze or Hoffmeister, and
final alkaline hydrolysis.
The products, i.e. residues, thus obtained were different in essential
points from the celluloses isolated from the tissues of phanerogams
similarly treated. Only in exceptional cases do they give blue reactions
with iodine in presence of zinc chloride or sulphuric acid. The
colourations are brown to red. They resist the action of cuprammonium
solutions. They are for the most part soluble in alkaline hydrate
solution (5-10 p.ct. NaOH) in the cold. They give small yields (1-2
p.ct.) of furfural on boiling with 10 p.ct. HCl.Aq.
Elementary analyses gave the following results, which are important in
establishing the presence of a notable proportion of nitrogen, which has
certainly been overlooked by the earlier observers:--
_________________________________________________________
| | | | |
| 'Cellulose' or residue from | C | H | N |
|______________________________________|______|_____|_____|
| | | | |
| Boletus edulis (Schulze process) | 42.4 | 6.5 | 3.9 |
| Boletus edulis (Hoffmeister process) | 44.6 | 6.3 | 3.6 |
| Polyporus off. | 43.7 | 6.5 | 0.7 |
| Cantharellus cib. | 44.9 | 6.8 | 3.0 |
| Agaricus campestris | 44.3 | 6.6 | 3.6 |
| Botrytis | 42.1 | 6.3 | 3.9 |
| Penicillium glaucum | | | 3.3 |
| Morchella esculenta | | | 2.5 |
|______________________________________|______|_____|_____|
It is next shown that this residual nitrogen is not in the form of
residual proteids (1) by direct tests, all of which gave negative
results, and (2) indirectly by the high degree of resistance to both
alkaline and acid hydrolysis. The 'celluloses' are attacked by boiling
dilute acids (1 p.ct. H_{2}SO_{4}), losing in weight from 10 to 23
p.ct., the dissolved products having a cupric reduction value about 50
p.ct. that of an equal weight of dextrose. As an extreme hydrolytic
treatment the products were dissolved in 70 p.ct. H_{2}SO_{4}, allowed
to stand 24 hours, then considerably diluted (to 3 p.ct. H_{2}SO_{4})
and boiled to complete the inversion. The yields of glucose, calculated
from the cupric reduction, were as follows:--
Boletus edulis 65.2 p.ct.
Polyporus off. 94.7 "
Agaricus campestris 59.1 "
Morchella esculenta 60.1 "
Cantharellus cib. 64.9 "
Botrytis 60.8 "
It will be noted that the exceptionally high yield from the Polyporus
cellulose is correlated with its exceptionally low nitrogen. By actual
isolation of a crystalline dextrorotary sugar, by preparations of
osazone and conversion into saccharic acid, it was proved that dextrose
was the main product of hydrolysis. The second main product was shown to
be acetic acid, the yield of which amounted to 8 p.ct. in several cases.
Generally, therefore, it is proved that the more resistant tissue
constituents of the fungi are not cellulose, but a complex of
carbohydrates and nitrogenous groups in combination, the former being
resolved into glucoses by acid hydrolysis, and the latter yielding
acetic acid as a characteristic product of resolution together with the
nitrogenous groups in the form of an uncrystallisable syrup.
In the further prosecution of these investigations (2) the author
proceeded from the supposition of the identity of the nitrogenous
complex of the original with chitin, and adopted the method of
Ledderhose (Ztschr. Physiol. Chem. 2, 213) for the isolation of
glucosamin hydrochloride, which he succeeded in obtaining in the
crystalline form. In the meantime E. Gilson had shown that these tissue
substances in 'fusion' with alkaline hydrates yield a residue of a
nitrogenous product (C_{14}H_{28}N_{2}O_{10}), which is soluble in
dilute acids [Recherches Chim. sur la Membrane Cellulaire des
Champignons, La Cellule, v. II, pt. 1]. This residue, which was termed
mycosin by Gilson, has been similarly isolated by the author. It is
proved, therefore, that the tissues of the fungi do contain a product
resembling chitin. [See also Gilson, Compt. Rend. 120, 1000.] This
constituent is in intimate union with the carbohydrate complex, which is
resolved similarly to the hemicelluloses. Various intermediate terms of
the hydrolytic series have been isolated. But the only fully identified
product of resolution is the dextrose which finally results.
UEBER DIE KOHLENHYDRATE D. HEFE.
E. SALKOWSKI (Berl. Ber., 27, 3325).
~ON THE CARBOHYDRATES OF YEAST.~
The author has isolated the more resistant constituents of the
cell-membrane by boiling with dilute alkalis, and exhaustively purifying
with alcohol and ether.
The residue was only a small percentage (3-4 p.ct) of the original, and
retained only 0.45 p.ct. N.
It was heated in a digester with water at 2-3 atm. steam-pressure, and
thus resolved into approximately equal portions of soluble cellulose
(a) and insoluble (b). The latter, giving no colour-reaction with
iodine, is termed achroocellulose; the former reacts, and is therefore
termed erythrocellulose. The former is easily separated from its
opalescent solution. It has the empirical composition of cellulose. In
the soluble form it resembles glycogen. The achroocellulose is isolated
in the form of horny or agglomerated masses. It appears to be resolved
by ultimate hydrolysis into dextrose and mannose.