NationalLibraryOfScotland/medical-history-of-british-india huggingface dataset:
Schistosoma japonicum KATSURADA IN INDIA
149
0.2mm
Lateral view of Schistosoma japonicum.
Although the schistosome group on account of its extreme economic importance
has evoked in recent years considerable interest and has been an object of investiga-
tion at several places in this country the occurrence of an adult Schistosoma japoni-
cum has not, up to the moment, been recorded from any host in India. It is, how-
ever, very significant to note in this connection that Sewell [1919] described
cercaria resembling in almost all the details that of S. japonicum from the molluscs
Indoplanorbis exuslus Desh. and Limnœa amygdalum Troschel in Calcutta. The
differences between this cercaria and that of S. japonicum were, to quote Sewell
" Very slightly smaller as regards body and a trifle longer in the tail, but owing to
Schistosoma japonicum
KATSURDA
IN
INDIA
151
limits of the same species. This unnecessarily adds to the worries of a systematist
in such a complicated and a chaotic group as the parasitic worms. In all such cases
it is a more desirable procedure to record different variations occurring under the
same species rather than to multiply several varieties for various deviations noticed.
The writer had adopted this procedure even on previous occasions in the cases of
Ornithobilharzia turkestanicum and Schistosoma spindalis.
It is rather surprising in the end to notice that in spite of the occurrence of
S. japonicum in pigs there exists up to the present moment no record of the presence
of this fluke in human beings in this country. It is, however, likely that future
investigation will reveal the presence of this parasite also in man like many other
porcine parasites which are common to human beings.
REFERENCES.
Bhalerao, G. D. (1932). On the identity of the schistosome found in cases of bovine nasal
granuloma and some observations on a few other members of the Schistosomidæ. Ind. J.
Vet. Sc. & Anim. Husb. 2, 338-356.
Brumpt, E. (1931). Description de deux Bilharzies de mammiferes Africains, Schistosoma
curassoni sp. inquir. et Schistosoma rodhani n. sp. Ann. Parasitol. 9, 325-338.
Montgomery, R. E. (1906). Observations on bilharziosis among animals in India. 2. J. Trop.
Vet. Sc., Calcutta, 1, 138-174.
Price, E. W. (1929). A synopsis of the trematode family Schistosomidæ with descriptions
of new genera and species. Proc. U. S. Nat. Mus. 75, 1-39.
Sewell, R. B. (1919). The possible occurrence of Schistosoma japonicum, Kasturada in India.
Rec. Ind. Mus. 16, 425-429.
SELECTED ARTICLES
THE DIGESTION AND UTILISATION OF CRUDE FIBRE.
BY
PROFESSOR ERNST MANGOLD, M.D., Ph.D.,
Institute of Animal Physiology, College of Agriculture, Berlin.
(Reprinted from Nutrition Abstracts and Reviews, Volume 3, No. 3, January 1934.)
Crude fibre may be defined as the sum of all those organic components of the
plant cell membrane and supporting structures which in chemical analysis of plant
food-stuffs remain after removal of crude protein, crude fat and N-free extractives.
The definition of crude fibre set up by Henneberg and Stohmann (44) is a conven-
tion, based on the method devised by them and known as the Weende method for
estimation of crude fibre, which consists of the residue after treatment with 1.25 per
cent. sulphuric acid, 1.25 per cent. potash, water, alcohol and ether. This includes,
like the plant cell membrane itself, a mixture of chemical substances, celluloses,
hemicelluloses (pentosans, hexosans) and encrusting substances (lignin, cutin, suberin,
pectins). Investigation of the chemical, and even more of the physical and struc-
tural, properties of these substances is as yet incomplete (cf. 93, 96, 62, 67).
The digestibility of crude fibre both by animals and man is greatly affected by
the wide differences, qualitative and quantitative, in make up of the cell membrane
from these components. Digestibility of crude fibre is of great importance with
regard to the utilisation of plant food-stuffs, for the energy supplied by
crude fibre, which consists chiefly of carbohydrates, can be utilised only if the fibre
is digested. Further, the contents of plant cells can be utilised only if cell mem-
branes, which are easily permeable to digestive enzymes only in the more delicate
structures, can be ruptured mechanically or chemically dissolved.
ENZYMIC DIGESTION.
In nature, solution of cellulose by animal digestive enzymes is of minor import-
ance. Cellulases and hemicellulases capable of achieving this, have been found by
Biedermann and Moritz (3, 4, 5) in the snail, Helix pomatia, and in the fresh water
crab, Potamobius astacus. According to Dore, Boynton and Miller (19, 7, 91) the
shipsworm, Teredo navalis, digests wood fibre by cellulase. Lewis and Jewell (74)
found hemicellulases in 20 different species of insects and the existence of cellulases
in protozoa must be assumed (V. Buddenbrock (12), p. 585).
( 152 )
THE DIGESTION AND UTILIZATION OF CRUDE
FIBRE
153
Digestion of the cellulose of lichens lichenin (63) in Helix (64), Potamobius (72)
and even in mice (141) and rabbits (136) has been found to be due to a digestive
lichenase. Lichenase occurs in lichens and other plants ; indeed, mobilisation of
reserve celluloses is dependent on the occurrence of cellulases and hemicellulases.
On the other hand, in animals, the cellulases which occur as enzymes in food,
contrary to the original view of Brown and Morris (10), do not take part in the
digestion of fibre (115), even if the animal body provides favourable conditions for
the action of plant cytases (145).
In almost all cases where animals eat much plant food, the chemical digestion
of fibre is due to the enzymes of symbiolic micro-organisms. Of these the most im-
portant are flagellate infusoria and bacteria. According to the observations of
Cleveland (13, 14), the digestion of wood by termites and by wood eating fish (15,
135), is due to the production of an active cellulase by intestinal flagellates.
Symbiosis with cellulose splitting bacteria occurs widely in man and animals
that subsist on plant food. In farm animals the bacterial digestion of fibre in the
feed plays an important part with regard both to the availability of plant cell
contents and to the utilisation of the energy of fibre.
The process of digestion of fibre is best understood in ruminants. It was first
observed by Sprengel (125), described by Haubner and Sussdorf (40), and subjected
to exact chemical study by Henneberg and Stohmann (44), who found in cattle a
digestibility of fibre in meadow hay of 57-65 per cent., in oat straw of 55 per cent.
Soon after Wildt (144) found a coefficient of digestibility of hay by sheep of 56.19
per cent. Popoff (95) demonstrated the formation of methane in the rumen ;
Zuntz showed in addition that similar putrefactive changes occur in the cæcum and
Hofmeister (51) that they are also carried out in the colon.
The bacterial nature of fibre digestion in the rumen and intestine of ruminants
was demonstrated by Ellenberger (20) and Scheunert (112, 113), and the nature of
the bacterial flora concerned was carefully studied by Ankersmit (2), Hopffe (59),
Henneberg (42, 43), Schiebich (121, 122). On the other hand, it was shown by
Mangold's work (83, 84), thus disposing of earlier views, that the infusoria of the
rumen take no significant part in digestion of fibre. It has been shown by Tap-
peiner (130, 131) and by Zuntz with Markoff (152, 88) and other collaborators, that
the end products of the bacterial fermentation of fibre are gases (CO 2 , CH 4 and H 2 )
and acids (acetic, lactic, butyric, isobutyric, valerianic, formic, propionic and suc-
cinic). Henneberg and Stohmann (44) assumed the occurrence of soluble inter-
mediary products which Zuntz (153) and Ellenberger (20) conjectured to be dextrins
and sugars. Woodman (145) isolated sugar from the products of bacterial fermenta-
E 2
154 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, II.
tion of fibre by horse fæces, and showed with Stewart (146, 148) that cellulose
is split in the rumen to cellobiose and then to glucose.
The acids arising from further degradation, according to Zuntz (150), are utilised
in the metabolism of the ruminant. This is true especially, of the fermentation
lactic acid (88, 29) ; Zuntz and Mallevre (79) believe that butyric and acetic acids
also serve as sources of energy.
Woodman (147) considers that fermentation acids may have a sparing effect
on the combustion of body fat, but regards them as of no significance for fat forma-
tion. He is also of opinion (145, 147) that, if utilisation of fermented fibre does not
occur through absorption of the sugar formed, the processes occurring in degra-
dation of cellulose by bacteria in the gastrointestinal tract of plant eaters are to be
regarded merely as incidental to digestion, and that the acids arising can be utilised
only by the bacteria themselves.
Fermentation in the rumen may give rise to different end products. Hen-
neberg and Stohmann showed (44, pp. 52, 389) with bullocks, and this has since been
confirmed, that a large addition of easily digestible substances such as molasses, cane
sugar or starch, reduces the digestibility of fibre. Zuntz (151) explains this on the
grounds that the bacteria ferment, instead of cellulose, the more easily attacked
starch and sugar, which consequently lose some of their value and are less well
utilised. Zuntz (152, 154) with Markoff (88) and other collaborators, also showed
that addition of sugar to the contents of the rumen increased fermentation processes
threefold but depressed digestion in cattle.
COEFFICIENTS OF DIGESTIBILITY BY FARM ANIMALS.
Coefficients of digestibility of fibre for the numerous farm feedingstuffs, as
determined with ruminants and other farm animals in many feeding and metabolism
experiments cannot here be dealt with in detail. Reference may be made to the
tables of Kellner, Armsby, Forbes, Hansson and others.
For the horse, the digestibility of fibre in a ration of oats and chopped hay was
found by Zuntz and Lehmann (156) to be 13.85—32.59 per cent. Cellulose is not
dissolved in the stomach (117, p. 25), but only in the caecum (52, 110, 111, 114) and
colon. The fermentation of cellulose shown by Ellenberger and Hofmeister (21) to
occur in the contents of the lower ileum, is insignificant in amount (117). More
recent work by Teschner (132), Hotzel (50), Wrede (149) and Engler (22) from the
Ehrenberg Institute, shows a digestibility for draught horses of 21.48 per cent. for
oat meal ; 28.36 for straw ; 30-36.8 for hay ; 39 for steamed potatoes ; 52.40 for potato
silage. All values were considerably reduced by simultaneous feeding of molasses.
THE DIGESTION AND UTILIZATION OF CRUDE FIBRE
155
Digestion of crude fibre in the pig does not occur either in the stomach or
the small intestine, but only in the caecum and colon (111, 73). Degradation here
also is by bacterial action; extracts of mucosa are inactive (111).
With reference to the digestibility of the fibre of different feedingstuffs by pigs,
special reference may be made to the extensive investigations of Honcamp (e.g., 57).
On account of the wide variations in individual experiments, as shown in those of
Mangold and Stotz (87) with rye meal, it is hardly possible to give general averages
for the digestibility of fibre in different feedingstuffs. Thus, for instance, for fibre
in rye meal the following values have been found: Kellner, 2.3; Lehmann, 10;
Honcamp, 19.7 (11.9—27.4); Mangold and Stotz, 25.66 (0.0—36.06) per cent.
The reason for these wide variations in fermentation of fibre in the pig is
probably to be found in the changes of intestinal bacteria with the nature of the
ration, changes similar to those found in the dog and in man, and in the effect of
differences in the physical state of the feed.
ENERGY VALUE AND UTILISATION.
From the point of view of the energy value and utilisation of fibre by animals,
it is important that fibre is broken down by bacterial digestion to the same end
products as are starch and sugar. The stomach and intestinal gases produced by
this bacterial fermentation, and also part of the acids, are not utilised in the animal
body, and are lost. The same value may be assumed for such part of these products
as is absorbed as sugar or fatty acids or used for constructive purposes by the
bacteria themselves. In agreement with this view, Kellner (66) in 8 experiments on
bullocks with 1 kg. potato starch or straw or cane sugar found weight increases of
248, 253 and 188 g. respectively, indicating an energy utilisation of 56.4 per cent. for
starch and 57 per cent. for fibre with fermentation losses of 43.6 per cent. for starch
and 43 per cent. for fibre. Kellner found also that the energy value of the digestible
part of fibre corresponded fairly closely with that of cellulose and pentosans. For
methane, according to Kellner (66, p. 95), 14 per cent. must be deducted, so that
the utilisable energy of 1 g. fibre is 3,599 calories. Similarly, Henneberg and
Stohmann (45) calculate 1 g. fibre as equivalent to 3,519 calories (cf. also 55).
It has, however, been pointed out by different writers that the doctrine of
equal net energy values for fibre and starch in ruminants is, in some way, unsatis-
factory. In the first place as Zuntz (150) showed as early as 1879, the digestion of
fibre, unlike that of starch, involves work, so that the net energy is the metabolisable
energy minus the energy used in digestion. Zuntz (36) estimates the loss in
ruminants per 1 g. fibre as 0.14 Cal.; Ustjanzew estimates 0.31 Cal. for chewing
156 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, II.
and cudding and 0.5 Cal. for intestinal work, or, altogether 0.64 Cal. (17) or 0.84
Cal. (138), i.e., for example, per kg. hay in ruminants 94.2—111.7 Cal. (68). The loss
in horses is higher, 167 Cal., since here the more intensive chewing exceeds the work
of rumination and fermentation in the rumen. According to Zuntz, Lehmann (156)
and Hagemann (155) the work of chewing and digesting the fibre of a normal ration
in horses represents 9 per cent., or for 1 g. fibre, 2.65 Cal. In straw feeding, more
energy may be used for digestion than that supplied by the nutrients absorbed
(155, p. 280).
In the pig, the utilisable value of fibre is lower, compared with starch and sugar,
since less of these is lost in fermentation; Fingerling (24) found for 1 kg. starch,
355 g. as compared with 248 g. for fibre, giving a value for 1 g. fibre of 4186.2 cal.
OTHER ANIMALS AND MAN.
In the rabbit the caecum is again the site of fibre digestion (157, 137) ; v.
Knieriem (69) Konig (70) and Thomas and Pringsheim (134) found a fairly high
digestibility of crude fibre, cellulose and pentosans, amounting in carrots to 65.3 and
in cabbage leaves to 77.99 per cent.
Experiments by Fredrich (26) working under Lintzel at this Institute, showed
that rats can utilise fibre to a considerable extent. White rats on a mixed diet
containing 3.3 per cent. crude fibre in wheat and barley meal and potato flakes,
showed a coefficient of digestibility of 46.54 per cent., with variations from 38.95 to
51.92 per cent.
Some workers have found crude fibre or cellulose, largely indigestible by the
dog (69, 118, 119, 116, 48, 134). Rubner however (101, 103, 104, 106), studying the
utilisation by the dog of different additions to a meat diet, estimated the digestibility
of the plant cell membrane in three fractions, cellulose, pentosans and residue, and
found considerable degrees of digestibility. The coefficient of digestibility of paper
was 20—25 per cent., that of birch sawdust 30—40 per cent. and of wheat bran 25
per cent. Waentig (140), using Weende crude fibre from rye straw, found digesti-
bility zero when the fibre was baked in bread, but 9.7 per cent. when added to a
mash of potato flakes, while untreated rye straw in bread gave a digestibility of 10
per cent.
Thomas and Pringsheim (134), using filter paper instead of Weende fibre, or pure
cellulose prepared by Cross and Bevan's method (16), got completely negative
results. They explain the fact that results are sometimes positive and sometimes
negative as due to variation in the intestinal flora, the dog evidently being at times
without cellulose splitting bacteria. Thus it may be assumed that, although the
THE DIGESTION AND UTILIZATION OF CRUDE
FIBRE
157
digestive system of carnivores is not naturally adapted for plant food, a dog may
develop an intestinal flora which makes possible a certain amount of digestion of
fibre. The house dog is fed as an omnivorous animal and often with much plant
food so that, with this food, it will also ingest cellulose splitting bacteria. Bacterial
fermentation in this case will probably attack chiefly the more delicate vegetable
celluloses which are also digestible by man. But the fibre of potatoes and cereal
grains were found to be largely digestible in experiments of Lossl at this Institute
on fox terriers, although there were wide variations in different experiments. Of
the Weende fibre, the dogs digested; from barley meal 7.67—33.53 ; potato flakes,
15.37-23.07; boiled potatoes, 3.27—86.83 ; rye meal, 14.54-24.28 ; wheat meal,
2.92—87.52 and rice, 25.24—80.05 per cent.
These wide variations in fibre digestion by the dog appear understandable in the
light of the possible differences in bacterial flora in the intestine and the similar
observations on the wide individual differences in fibre digestion in man, In man,
also, the alimentary tract normally digests cellulose in different degrees depending
on its origin, age and hardness; sometimes digestion may be almost complete.
On account of the fact that most investigations have been made on a limited
number of subject with only single experiments, and of the large range of variation,
it is impossible to give figures for the average digestibility by man of fibre in
different foodstuffs. Weiske (143) was the first to study fibre digestion in man,
and he found in two subjects, on pre- and post-experimental diet free from cellulose,
digestibility coefficients of 47.3 and 62.7 per cent. for carrots, celery and cabbage.
v. Knieriem (69) found 25.32 per cent. digestibility for fibre of lettuce. Lohrisch
(76) on the basis of a few 1-2 day experiments on 3 subjects, gives the following
fibre digestibilities . white cabbage, 100 ; carrots, 95 ; spinach, 90 ; bread, 59-85 ;
split peas, 45 per cent. Rubner carried out numerous single experiments on human
subjects in his studies of the digestibility of plant foods, using different kinds of
vegetables, fruits and bread. Of the chemical components of the cell membrane,
he found in some kinds of fruit and vegetables, that cellulose was 79.06, pentosan,
81.81 and residue, 82.86 per cent. digestible. For different types of bread the
corresponding figures were 32.81, 45.46 and 33.26 per cent. The cell membrane of
potatoes was particularly easily digested, a characteristic which justifies their
wide use as a foodstuff (108).
In the study of the digestion of fibre in man, microscopic examination of the
faeces is of particular importance. It is found that the delicate membranes of, for
instance, savoy cabbage or carrots (Rubner, 102) are completely digested ; those of
spinach, with the exception of the lignified fibres of the spiral vessels (35, 47), and
those of potatoes also to a great extent (1,129). Well lignified parts and cork are
not affected (101).
158 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ IV, II.
According to Rubner and Lindner (75) the aleurone cells of cereal grains pass
through the human digestive tract without solution of their cell walls and without
satisfactory digestion of the cell contents ; the same is true of the horse and sparrow
(75) and similar observations have been made by Mangold (80) and Kruger (71)
on poultry.
Undigested fibre, both by its own bulk and also because of increased intestinal
secretion in man and the dog, causes an increase in the volume of faeces (104, 105).
This is true in particular, when the bran content of bread is increased (105, 107);
the digestibility of fibre and of the pure cellulose and pentoses of bread is reduced,
in the case of rye bread from 58.7 to 46.1 per cent. (30, 105, 92.). If digestibility
is low increase of cellulose results in loss of energy value, since the loss of
calories in the faeces is larger than during low cellulose control periods (25).
In general, at least in man, the young non-lignified cell membrane of food plants
is much more easily attacked and digested by bacteria than older, lignified struc-
tures (49). In man the small intestine shares in this process, as has been shown
experimentally by Gosmann and van der Reis (31). These workers found that
raw or cooked cellulose can be broken down and rendered soluble, not only by the
bacteria from human faeces, as was shown by Khouvine, Delaunay and Hopffe,
such bacteria being capable according to Remy (98) of fermenting 42-94 per cent.
of fibre, but also by bacteria from the colon, and even the upper, middle and
lower parts of the small intestine, while Berkefeld filtrates are inactive. Since
samples taken by means of metal capsules from the empty small intestine were
active, these workers are inclined to the view that the human small intestine has
an obligate flora of cellulose fermenting bacteria. The part played by the small
intestine in digestion of fibre is confirmed by observations of Strauss (129) on
patients in whom the large intestine was excluded by operative measures.
With regard to individual differences in digestion of fibre and other factors which
influence it, and also with regard to the utilisation of the energy of cellulose, the
same general rules apply to man as have already been discussed or will be dealt
with later. The role of pentosans in human metabolism will be discussed below in
the section dealing with these substances.
For a long time it was not recognised that fibre can be digested by poultry (112 ;
27, page 143). It was commonly regarded as indigestible roughage (Durigen).
Mangold has, however, shown (81, 82) that this older view was the result of faulty
technique. and, in particular, of too short experimental periods. Further, more
detailed experiments of Katayama (65) on poultry, with different feedstuffs, in
which faecal and urinary excreta were collected separately by means of an artificial