THE CHEMICAL ACTIVITIES OF THE SOIL POPULATION AND THEIR RELATION TO
THE GROWING PLANT.
In the preceding chapters it is shown that the soil is normally
inhabited by a very mixed population of organisms, varying in size from
the smallest bacteria up to nematodes and others just visible to the
unaided eye, on to larger animals, and finally earthworms, which can
be readily seen and handled. These organisms all live in the soil, and
therefore must find in it the conditions necessary for their growth.
We have dealt in the first chapter with the supplies of water, air,
and heat, without which life is clearly impossible. Equally necessary
is the source of energy, for the organism requires energy material as
surely as the motor engine requires petrol, and it ceases to function
unless an adequate supply is forthcoming.
All the energy comes in the first instance from the sun, if we exclude
the unknown but probably small fraction coming from radio-active
elements. But this radiant energy is not utilisable by the soil
population, excepting surface algæ; it has to be transformed into
another kind. So far, chlorophyll is the only known transformer;
it fixes the energy of sunlight and stores it up in bodies like
hemicellulose, sugar, starch, protein, etc. The transformation is
imperfect; even the heaviest yielding crops grown under glass, in
conditions made as favourable as our knowledge permits, utilise only
about 4 per cent. of the total energy available during their period of
growth; in natural conditions not more than 0·4 per cent. is utilised.
Such as it is, however, the energy fixed in the plant represents all,
indeed more than all, that the soil organisms can obtain.
In the state of Nature, vegetation dies and is left on the soil. Two
things may then happen. It may become drawn into the soil by earthworms
and other agents; the energy supply is thus distributed in the soil
to serve the needs of the varied soil population. This is the normal
case, associated with the normal soil population and the normal flora.
If, however, the mingling agents are absent, the dead vegetation lies
like a mat on the surface of the soil, only partially decomposing,
unsuitable for the growth of most seedlings, and effectually preventing
most of the vegetation below from pushing a way through: thus there
comes to be no vegetation at all, or only a very restricted and special
flora. The soil population becomes also specialised. Peats and acid
grassland afford examples.
On the neutral grass plots at Rothamsted, the dead vegetation does not
accumulate on the surface but is rapidly decomposed or drawn into the
soil, leaving the surface of the earth bare and free for the growth
of seedlings. On the acid plots dead vegetation remains long on the
surface, blotting out all new growth excepting two or three grasses
which form underground runners capable of penetrating the mat, and
sorrel, the seedling roots of which seem to have the power of boring
through a fibrous layer of this sort. It is possible to remove the
mat entirely by bacterial action alone, if sufficient lime be added
periodically to make the reaction neutral, but failing these repeated
additions the mat persists.
We shall confine ourselves to the normal case where earthworms bring
the source of energy into the soil.
Directly the energy is available, it begins to be utilised. Two laws
govern the change. The first is well-known to biologists: it states
that the total energy of the system remains constant and can neither
be increased nor diminished except from outside; in other words, that
energy can be neither created nor destroyed. The second law is less
familiar: it is that energy once transformed to heat by one organism
cannot be used again by another. It is not destroyed; it remains
intact, but is useless to the organism. One cannot have an indefinite
chain of organisms living on each other’s excretory products; there was
a certain quantity of energy in the food eaten by the first, and no
more than this quantity can be got out whether one organism obtains the
whole or whether others share it.
The outside value for the amount of energy fixed in the soil is
obtainable by combustion of the soil in a calorimeter, but much of
this is not available to the soil organisms. The normal sedimentary
soils of England still contain decomposition products of the débris
of plants and animals originally deposited with them, but in the long
course of ages much of the extractable energy has been utilised. The
soil population is thus dependent on recently grown vegetation, and it
is therefore largely confined to the layer, usually in this country
about 6 inches thick, through which the recently dead vegetation is
distributed. Below this level there may be sufficient air, water,
temperature, etc., but there is insufficient source of energy for any
large population.
Unfortunately there is no ready means for distinguishing between the
total and the actually available quantity of energy in the soil. But
it is not difficult, by adopting the Rothamsted analytical method, to
ascertain the approximate amount of energy that has been transformed in
a given period. The Rothamsted plots are periodically analysed and a
balance sheet is drawn up showing how much of each constituent has been
added to and removed from the soil in the intervening period. For two
of the Broadbalk plots the results are shown in Tables XV., XVI.
The dunged plot receives 14 tons farmyard manure per annum, a quantity
in excess of what would usually be given; the unmanured plot, on the
other hand, has received no manure for many years and is abnormally
poor. Normal soils lie somewhere between these limits, but tending
rather to the value for the dunged than for the unmanured plot. It will
be seen that each acre of the dunged land loses on an average 41,000
calories per day, while each acre of the unmanured land loses on an
average 2700 calories per day.
TABLE XV.--MATERIAL BALANCE SHEET: BROADBALK SOIL, ROTHAMSTED.
(LB. PER ACRE PER ANNUM.)
+-------------------------+-------------+---------------+
| | Farmyard | No Manure |
| |Manure Added.| Added. |
| +------+------+-------+-------+
| | C. | N. | C. | N. |
+-------------------------+------+------+-------+-------+
|Added in farmyard manure| 3600 | 200 | nil | nil |
|Added in stubble | 300 | 3 | 100 | 1 |
+-------------------------+------+------+-------+-------+
| Total added | 3900 | 203 | 100 | 1 |
|Taken from soil | nil | nil | 200 | nil |
|Stored in soil | 200 | 30 | nil | nil |
+-------------------------+------+------+-------+-------+
| Lost from soil | 3700 | 170 | 300 | nil[H]|
| Per cent. | 95 | 84 | 100 | nil |
+-------------------------+------+------+-------+-------+
Initial C : N ratio in farmyard manure, 18 : 1
Final C : N ratio in soil, 10 : 1.
[H] Gain of 6 lb. See p. 173.
TABLE XVI.--ANNUAL ENERGY CHANGES IN SOIL: BROADBALK. APPROXIMATE
VALUES ONLY.
MILLIONS OF KILO CALORIES PER ACRE PER ANNUM.
+---------------------------------+-------------+---------+
| | Farmyard |No Manure|
| |Manure Added.| Added. |
+---------------------------------+-------------+---------+
|Added in manure | 14 | nil |
|Added in stubble | 2 | 0·3 |
| +-------------+---------+
| Total added | 16 | 0·3 |
|Taken from soil | nil | 0·5-1 |
|Stored in soil | 0·5-1 | nil |
| +-------------+---------+
| Dissipated per annum | 15 | 1 |
+---------------------------------+-------------+---------+
|Per day: calories | 41,000 | 2700 |
|Equivalent to | 12 men. | ¾ man. |
|The human food grown provides for| 2 men. | ½ man. |
+---------------------------------+-------------+---------+
These numbers are interesting when we reflect that the human food
produced on the dunged land yields only 7000 calories per day, from
which it is clear that our agricultural efforts so far provide more
energy for the soil population, for which it was not intended, than for
ourselves.
The account is not complete; we have omitted all reference to the
oxidation of ammonia and of elements other than carbon. Nature
seems to be in an unexpectedly economical mood in the soil, and all
compounds which can be oxidised with liberation of energy seem to
have corresponding organisms capable of utilising them. Even phenol,
benzene, hydrogen, and marsh gas can all be oxidised and utilised as
energy sources by some of the soil population.
Even with this remarkable power the soil population has insufficient
energy to satisfy all its possibilities; our present knowledge
indicates that energy supply is, in this country at any rate, the
factor limiting the numbers of the population. Increases in the water
supply or the temperature of the soil produce no consistent effect on
the population, but directly the energy supply is increased the numbers
at once rise.
MATERIAL CHANGES.
These transformations of energy involve transformations of matter.
The original plant residues may be divided roughly into substances
forming the structure of the plant, such as the hemicelluloses, the
pentosans, gums, and the contents of the cell--the protoplasm and the
storage products, protein; in addition, there are smaller quantities of
fats and waxes and other constituents. Some of the easily-decomposable
carbohydrates never reach the soil at all, being broken down by
intracellular respiration or attack of micro-organisms. But much of the
structure material--hemicelluloses, pentosans, etc.--remains.
Once the plant residues pass through the earthworm bodies they become
completely disintegrated and lose all signs of structure.
The only visible product so far known is humus, the black sticky
substance characteristic of soil and of manure. Two modes of formation
have been suggested. Carbohydrates, sugars, pentosans, etc., are
known to yield furfuraldehyde or hydroxymethylfurfuraldehyde on
decomposition, and it has been shown at Rothamsted that this readily
condenses to form a humus-like body, if not humus itself. In the
laboratory the reaction is effected in presence of acid, but even
amino-acids suffice. All the necessary conditions occur in the soil,
and humus formation may proceed in this way.
Some of the structure material--the lignin--contains aromatic ring
groupings. Fischer and Schrader have shown that in alkaline conditions
these ring substances absorb oxygen and form something very like humus.
It is quite possible that humus formation also proceeds in the soil
in this way. Whether the two products are chemically identical is not
known.
The scheme can be represented thus:--
Cell structure material
|
+----------------+----------------+
| |
Aliphatic Aromatic
(Hemicelluloses, (Lignin, etc.,
Pentosans, etc.) in presence of
| oxygen and under
+-------+------------+ aerobic conditions)
| | |
Fatty acids Furfuraldehyde |
| or |
| Hydroxymethylfurfuraldehyde |
| (in presence of acid) |
| · |
| · |
| · |
| · |
| · |
| · |
| · |
| · |
| · |
↓ ↘ ↓
Calcium carbonate. Humus.
The disintegration of the cell and the first stages in the
decomposition of the structure material are almost certainly brought
about by micro-organisms. Whether they complete the process is not
known: purely chemical agencies could easily account for part.
The decomposition of protein in the soil has not been studied in any
detail. From what is known of the acid hydrolysis and the putrefactive
decompositions, however, it is not difficult to draw up a scheme which,
at any rate, accords with the facts at present known. It is probable
that the protein gives rise to amino-acids, which then break down by
one of the known general reactions.
Two types of non-nitrogenous products may be expected: The aliphatic
amino-acids give rise to ammonia and fatty acids; these form
calcium salts which break down to calcium carbonate. The aromatic
amino-acids--tyrosin, phenylalanine, etc.--which would account for
about 6 per cent. of the nitrogen of vegetable proteins, would be
expected to give ammonia and phenolic substances. Now phenols are
poisonous to plants and if no method existed for their removal the
accumulation would ultimately render the soil sterile. Matters would be
even worse on cultivated soils, since cows’ urine, which enters into
the composition of farmyard manure and is the chief constituent of
liquid manure, contains, according to Mooser, no less than 0·25 to 0·77
grams of _p_-cresol per litre,[I] a quantity three to ten times that
present in human urine. Fortunately this contingency never arises, for
the soil contains a remarkable set of organisms capable of decomposing
the phenols and leaving the soil entirely suitable for plant growth.
This affords an interesting case of an organism--in this case the
plant--growing well in a medium in spite of some adverse condition, not
because it is specially adapted to meet this condition, but because
some wholly different agent removes it.
[I] Mooser, Zeitschrift physiol. Chem., 1909, lxiii., 176. No phenol
was found. It is possible that the _p_-cresol is not entirely derived
from the protein, but that some comes from the glucosides in the
animals’ food.
Other ring compounds, e.g. pyrrol, arise in smaller quantity in the
decomposition of protein, but their fate in the soil is not known.
We may summarise the probable changes of the protein as follows:--
Protein.
+-------------------+------------------+
| | |
Aliphatic Aromatic Other
amino-acids amino-acids compounds
| | (Pyrrol, etc.)
+--------+--------+ +--------+--------+
| | | |
Fatty acids and Ammonia Phenolic
hydroxy acids | compounds
| Nitrite |
| | |
| | |
↓ ↓ ↓
Calcium Nitrate CO₂
carbonate
It must be admitted that the evidence is indirect. The rate of
oxidation of ammonia by bacteria in the soil is more rapid than the
rate of formation, so that ammonia is practically never found in the
soil in more than minimal amounts (1 or 2 parts per 1,000,000); indeed,
the only evidence of its formation was for a long time the fact that
no compound other than ammonia could be oxidised by the nitrifying
organism. It has, however, since been shown at Rothamsted that ammonia
accumulates in soils in which the nitrifying organism has been killed.
Nothing is known of the mechanism of the oxidation of ammonia beyond
the fact that it is biological; the reaction is not easily effected
chemically at ordinary temperatures. Possibly the organism assimilates
ammonia at one end of a chain of metabolic processes and excretes
nitrates at the other. Or, the reaction may be simply a straight
oxidation for energy purposes, the ammonia changing to hydroxylamine
and then to nitrous and nitric acids.
The nitrate does not remain long in the soil. Some is taken up by the
plant and some is washed out from the soil. Part, however, either of
the nitrate itself or of one of its precursors is converted into an
insoluble form: probably it is changed into protein by the action of
micro-organisms; it then goes through the whole process once more.
These are the general outlines; they present no particular chemical
difficulties. When we come to details, however, there is much that
cannot be understood.
First of all, there is the slow rate at which complex nitrogen
compounds disappear from the soil in comparison with the rate of
oxidation of the carbon. Thus, in the original plant residues, there
is some forty times as much carbon as nitrogen: before they have been
long in the soil there is only ten times as much carbon as nitrogen;
this seems to be the stable position. What is the reason for this
preferential oxidation of the carbon? No explanation can yet be given.
[Illustration: FIG. 24.
X-axis: 1887-8 1890-1 1900-1 1910-11
Y-axis: ℔ per acre]
An equally difficult problem arises in connection with the length of
time the process will continue. Decomposition of the nitrogen compounds
never seems to be complete in the soil; it dribbles on interminably.
In the year 1870 Lawes and Gilbert cut off a block of soil from its
surroundings and undermined it so that the drainage water could be
collected and analysed. The soil has been kept free from vegetation
or addition of nitrogen compounds from that time till now; yet it has
never failed to yield nitrates, and the annual yield falls off only
very slowly (Fig. 24). This same peculiarity is seen in the yield of
crops on unmanured land: it decreases, but very gradually; even after
eighty years the process is far from complete, and there is no sign
that it will ever come to an end.
TABLE XVII.--APPROXIMATE LOSS OF NITROGEN FROM CULTIVATED SOILS:
BROADBALK WHEAT FIELD, ROTHAMSTED, FORTY-NINE YEARS (1865-1914.)
+------------------------+---------------------+---------------------+
| | Rich Soil: Plot 2. | Poor Soil: Plot 3. |
| | Lb. per Acre. | Lb. per Acre. |
+------------------------+---------------------+---------------------+
|Nitrogen in soil in 1865|·175 per cent. = 4340|·105 per cent. = 2720|
|Nitrogen added in | | |
|manure, rain (5 lb. per | | |
|annum), and seed (2 lb. | | |
|per annum) | 10,140 | 340 |
+------------------------+---------------------+---------------------+
|Nitrogen expected in | | |
|1914 | 14,480 | 3060 |
|Nitrogen found in 1914 |·259 per cent. = 5950|·095 per cent. = 2590|
+------------------------+---------------------+---------------------+
|Loss from soil | 8530 | 470 |
|Nitrogen accounted for | | |
|in crops | 2500 | 750 |
+------------------------+---------------------+---------------------+
|Balance, being dead loss| 6030 | -280[J] |
|Annual dead loss | 123 | - 6[J] |
+------------------------+---------------------+---------------------+
[J] Gains. Possibly the result of bacterial action.
A further remarkable fact connected with the decomposition of the
nitrogen compounds is that it seems invariably to be accompanied by
an evolution of gaseous nitrogen. Apparently there are two cases.
Under anaerobic conditions many of the soil organisms have the power
of obtaining their necessary oxygen from nitrates, thereby causing
a change in the molecule which leads in some cases to liberation of
gaseous nitrogen; but the same result seems to be attained in aerobic
conditions, especially when carbon is being rapidly oxidised.
It is possible that the reaction is the same, and that in spite of the
general aerobic conditions there is locally an anaerobic atmosphere.
But it is also possible that some direct oxidation of protein or
amino-acids may yield gaseous nitrogen. However it is brought about
it affects a considerable proportion of the entire stock of nitrogen,
and it becomes more serious as cultivation is intensified. Thus, on
the Broadbalk plot receiving farmyard manure the loss is particularly
heavy; on the unmanured plot it cannot be detected. The nitrogen
balance-sheet is shown in Table XVII.
The oxidation of carbonaceous matter, however, is not invariably
accompanied by a net loss of nitrogen; in other circumstances there is
a net gain. In natural conditions there seems always to have been some
leguminous vegetation growing; the gain may, therefore, be ascribed
to the activity of the nodule organism. In pot experiments, however,
it has been found possible, by adding sugar to the soil, to obtain
gains of nitrogen where there is no leguminous vegetation, and this is
attributed to the activity of Azotobacter.
The nitrogen cycle as observed in the soil is as follows:--
+--------------→ Protein ←----------------+
| · · |
| · · |
| · · |
By certain| · · |
organisms | | | |By Azotobacter,
and by | ↓ | |Clostridium,
growing | Ammonia | Mechanism |nodule organisms,
plants | | | uncertain |etc.
| ↓ | |
| Nitrite | |
| | ↓ |
| ↓ Gaseous |
+------- Nitrate ------→ Nitrogen --------+
By denitrifying organisms
There has been but little study of the process of decomposition of the
other compounds in plants. Part, if not all, of the sulphur is known
to appear as sulphate, and some of the phosphorus as phosphate. It is
certain that the plant constituents decompose, for there is no sign of
their accumulation in the soil. They may exert transitory effects, but
there is nothing to show permanent continuance. The toxic conditions
which cause trouble in working with pure cultures of organisms in
specific cultures media do not, so far as is known, arise in the soil.
All attempts to find bacterio-toxins or plant toxins in normal soils
have failed. The product toxic to one organism seems to be a useful
nutrient to another, and so the mixed population keeps the soil healthy
for all its members.
There is little precise knowledge as to the part played by the
different members of the soil population in bringing about these
changes.
We know in a general way that earthworms effect the distribution of
the plant residues in the soil, and serve to disintegrate them; there
is no evidence, however, that they play any indispensable part in the
decomposition. Many root and other fragments do not go through this
process; observation shows that fungi can force a way in, and they may
be followed by nematodes which continue the disintegration. Possibly
some of the flagellates help, and certainly the bacteria do. After that
nothing is certain. We cannot, with certainty, assign any particular
reaction in the decomposition to any specific organism, with the
exception of the oxidation of the phenolic substances, the conversion
of ammonia to nitrite and nitrate, and the fixation of nitrogen. With
these exceptions many organisms seem capable of bringing about the
reactions, and indeed some of the reactions may be purely chemical and
independent of biological agencies.
The relationships between the soil population and soil fertility are
readily stated in general outline, but they are by no means clear cut
when one comes to details; fertility is a complex property, and some
of its factors are independent of soil micro-organisms.
The general relationship between plants and soil organisms is one of
complete mutual interdependence. The growing plant fixes the sun’s
energy and converts it into a form utilisable by the soil organisms;
without the plant they could not exist. The plant is equally dependent
on the soil organisms in at least two directions: their scavenging
action removes the dead vegetation which would, if accumulated on the
surface of the soil, effectively prevent most plants from growing.
Further, the plant is dependent on the soil population for supplies
of nitrates. Nothing is known about the relative efficiencies of the
various soil organisms as scavengers. Numerous fungi and bacteria are
effective producers of ammonia, the precursor of nitrates; it is not
known, however, whether flagellates and such higher forms as nematodes
act in this way.
This widespread power of producing ammonia makes it impossible in our
present knowledge to regard any particular group of organisms as _par
excellence_ promoters of fertility. Indeed, it is safest not to attempt
to do so. The primary purpose of the activities of a soil organism
is to obtain energy and cell material for itself; any benefit to the
plant is purely incidental. For cell material it must have nitrogen
and phosphorus; here it competes with the plant. If it produces more
ammonia than it utilises--in other words, if it is driven to nitrogen
compounds for its energy, then the plant benefits. If, on the other
hand, it absorbs more ammonia than it produces, as happens when it
derives its energy from non-nitrogenous substances, the plant suffers.
Thus, addition of peptone to the soil or an increase in bacterial
numbers effected without addition of external energy (e.g. by partial
sterilisation) leads to increased ammonia supply, and, therefore,
to increased fertility. But addition of sugar to the soil causes so
great an increase of numbers of bacteria and other organisms that
considerable absorption of ammonia and nitrate occurs, and fertility
is for a time depressed.
Both actions proceed in soils partially sterilised by organic
substances, such as phenol, which are utilised by some of the soil
organisms; there is first a great rise in numbers of these particular
organisms with a depression of ammonia and nitrate, then a drop to the
new level, higher than the old one, and an increased production of
ammonia and nitrate resulting from the partial sterilisation effects.
We must then regard the soil population as concerned entirely to
maintain itself, and only incidently benefiting the plant, sometimes,
indeed, injuring it; always essential, yet always taking its toll, and
sometimes a heavy toll, of the plant nutrients it produces.
This effect makes it difficult to deduce simple quantitative
relationships between bacterial activity and soil fertility, and the
difficulty is increased by the fact that bacteria and plants may both
be injured or benefited by the same causes, so that high bacterial
numbers in a fertile soil would not necessarily be the cause, but might
be simply the result of fertility.
The circumstance that certain soil organisms--bacteria, algæ, and
fungi--themselves assimilate ammonia and nitrate may account for
the remarkable slowness of nitrate accumulation, to which reference
has already been made. The protein formed from the assimilated
nitrogen remains in the bodies of the organisms, living or dead, till
decomposition sets in. It is not difficult to picture a cycle of events
in which much of the nitrate formed is at once reabsorbed by other
organisms, and only little is actually thrown off into the soil. Such a
process might continue almost interminably so long as any carbonaceous
material remained.
Finally, we come to the very interesting problem--is it possible to
control the population of the soil?
The problem may seem superfluous in view of the difficulties just
mentioned. Some aspects of it, however, are fairly clearly defined.
In the first instance, some organisms appear to be wholly harmful to
the plant; among them are parasitic eelworms and fungi, and bacteria
causing disease.
Control of these organisms can be brought about by partial
sterilisation, and of all methods heat is the most effective, but it
is costly, and attempts are now being made to replace it by chemical
treatment. The results are promising, but the investigation is
laborious; the organisms show specific relationships, and in finding
a sufficiently potent and convenient poison it is necessary in each
case to make an investigation into the relationship between chemical
constitution and toxicity to the particular organism concerned.
Formaldehyde is usually potent against fungi, and the cresols, and
particularly their chlor- and chloronitro-derivatives, are potent
against animals (eelworms, etc.).
One group of organisms is wholly beneficial, those associated with
leguminous plants. Attempts have been made to increase their activities
by inoculating the soil with more vigorous strains. The practical
difficulties still remain very considerable, but there is hope that
they may be overcome.
It is also possible to shift the balance of the soil population in
certain directions. Special groups of soil organisms can be caused
to multiply temporarily, if not permanently, by satisfying their
particular requirements. Thus, when a soil has been heated above 100°
C. it becomes specially suited to the growth of fungi, and quite
unsuited to certain bacteria such as the nitrifying organisms and
others; if this heated soil is infected with a normal soil population
the fungi develop to a remarkable extent. The nodule organisms appear
to be stimulated by addition of farmyard manure and of phosphates, and
the phenol-destroying organisms by successive small additions of phenol.
Finally, quite apart from the control of disease organisms, it is
possible to alter the soil population considerably by partial
sterilisation, using a temperature of only about 60° C., or a poison
like toluene that favours few of the soil organisms. This problem has
already been discussed in Chapter I.
The control of the soil population is still only in its infancy, but
it already promises useful developments. It cannot, however, be too
strongly insisted that the only sure basis of control is knowledge, and
we cannot hope to push control further till we have learned much more
about the soil population than we know at present.
AUTHOR INDEX.
ADAMETZ, 118.
Adams, 158.
Aiyer, 113.
Appel, 133.
Artari, 107.
Ashby, 42.
BARTHEL, 24.
Beijerinck, 6, 37, 41, 42, 46, 107.
Berthelot, 5, 6, 41.
Bewley, 47, 51, 132.
Bezssonoff, 69.
Boas, 138.
Bokorny, 138.
Bonazzi, 45.
Boresch, 107.
Boussingault, 3.
Bredemann, 24.
Bristol, 106.
Brizi, 113.
Brown and Halversen, 127.
Burgess, 41.
Burrill, 48.
Bussey, Peters and Ulrich, 132.
Butkevitch, 138, 139.
Butler, 132.
CAMERON, 150, 158.
Chodat, 107.
Christensen, 46.
Clayton, 28, 43.
Coleman, 127, 136.
Conn, 23, 54, 61, 123.
Cramer, 39.
Crump, 57, 79, 80.
Cunningham, 69.
Cutler, 57, 58, 78, 80.
DALE, 118, 121.
Darwin, 153.
Dascewska, 134.
De Bruyn, 132.
van Delden, 42.
Delf, 87.
Doryland, 33, 40.
Dox, 138.
Dox and Neidig, 134.
Drummond, 160.
Duggar and Davis, 135.
Duvaine, 20.
EHRENBERG, 138.
Ehrlich and Jacobsen, 138.
Esmarch, 102, 103.
FABRICIUS, 61.
Feilitzen, 61.
Fischer, 118, 126.
Forte, 101.
Frank, 132.
Fritsch, 112.
GAINEY, 46.
Gillespie and Hurst, 140.
Goddard, 118, 120, 121.
Golding, 49.
Goodey, 68, 73, 79, 105.
Greaves, 42, 61.
Green, 37.
Grintzesco, 107.
Groenewege, 42.
HAGEM, 118, 121, 136, 138, 139.
Hamilton, 158, 159.
Hansen, 48.
Hanzawa, 43.
Harrison, 113.
Heinze, 139.
Hellriegel, 5, 6, 46.
Hensen, 100.
Hesselmann, 36.
Hill, 94.
Hiltner, 23.
Hopkins, 36.
Hutchinson, C. M., 42.
Hutchinson, H. B., 27, 43, 47, 51, 57, 105.
VAN ITERSON, 133.
JENSEN, 118, 132.
Jewson, 123.
Joffe, 37.
Jones, D. H. and Murdock, 127.
Jones, L. R., 140.
KAPPEN, 136.
Karrer, 105.
Kaserer, 27.
Klöcker, 134.
Koch, A., 44, 134.
Koch, R., 20, 53.
Kofoid, 88.
Kohshi, 134.
Kopeloff, 118, 136.
Kossowitsch, 111.
Krainskii, 44.
Krzeminiewski, 43.
Kufferath, 107.
LATHAM, 135.
Laurent, 136.
Lawes and Gilbert, 5.
Lebedeff, 27.
Leeuwenhoeck, 20.
Lendner, 118.
Lipman, C. B., 41, 42, 44, 54.
Lipman, J. G., Blair, Owen, and McLean, 94.
Löhnis, 22, 43, 69, 136.
MAGNUS, 107.
Malpighi, 46.
Marchal, 34, 136.
Martin, 73.
Martin and Lewin, 69.
McBeth, 28, 134.
McBeth and Scales, 118, 140.
McLean and Wilson, 118, 136.
Mockeridge, 43.
Moore, G. T., 105.
Morris, 150, 151, 162.
Muntz and Coudon, 118, 136.
NABOKICH, 27.
Nagaoka, 38.
Nakano, 107.
Nasir, 94, 95.
Neller, 137.
OMELIANSKI, 27, 42.
Orla-Jensen, 26, 35.
Otto, 133.
Oudemans and Koning, 118.
PASTEUR, 3, 20.
Perey, 94.
Perotti, 136.
Petersen, 104.
Pillai, 43.
Potter and Snyder, 137, 138.
Povah, 138.
Pratt, 132.
Prescott, 61.
Pringsheim, 107.
RAMANN, 118.
Rathbun, 120.
Reh, 162.
Remy, 118.
Richards, 112.
Richardson, 159.
Ritter, 138.
Robbins, W. J., 109.
Robbins, W. W., 105.
Roussy, 134.
Russell, 112.
Russell and Hutchinson, 57, 66, 94.
SALUNSKOV, 42.
Sandon, 57, 75.
Scales, 28, 134.
Schellenberg, 133.
Schindler, 107.
Schloesing, 3, 4, 34.
Schmitz, 134.
Schramm, 111.
Servettaz, 109.
Seydel, 44.
Sherman, 69.
Shibata, 136.
Söhngen, 26, 27, 134.
TAKAHASHI, 118.
Taylor, 120.
Ternetz, 135.
Treub, 112.
Truffaut, 69.
VERKADE and Söhngen, 134.
Von Ubisch, 109.
WAKSMAN, 37, 118, 120, 121, 123, 125, 126, 134, 136.
Waksman and Cook, 136.
Wann, 111.
Warington, 4, 34.
Waynick, 42.
Welwitsch, 112.
Werkenthin, 120, 121.
West, 88, 105.
Whiting, 36.
Wilfarth, 46.
Winogradsky, 4, 6, 34, 41, 44.
SUBJECT INDEX.
_Absidia_, 121.
_Acarina_, 150, 151, 157.
Acid formation by Fungi, 139.
Acidity of soil, 17; effect on Actinomyces, 140; relation to
nitrification, 36.
_Actinomycetes_, 119, 134, 139.
Aeration of soil, effect on bacteria of, 61.
_Agriotes_, 150.
Air supply in soil, 17.
Algæ, agents causing disappearance of nitrate from soil, 12;
associations of, in soil, 105, 106; blue green, 102 _sqq._ (see also
Cyanophyceæ and Myxophyceæ); colonisation of new ground by, 112;
conditions of growth for, 101, 104, 107, 108; distribution of, 102,
104, 106, 109; economic significance of, 100, 102; filamentous,
106; flora of soil, 101, 112; formation of humus substances, 112;
fragmentation of filaments, 107, 110; frequency of occurrence, 102
_sqq._; glucose, effect of, on growth, 108, 109; green, 104 _sqq._
(see also Chlorophyceæ); importance in cultivation of rice, 113;
numbers in soil of, 109, 110; nutrition of, 107, 108, 110; producers,
of organic substance, 100; pure cultures of, 107, 111; relation to
gaseous interchange in soil, 113; relation to soil moisture, 112;
seasonal changes in numbers of, 88; subterranean, 105.
Alkaloids, as source of nitrogen for fungi, 138.
_Alternaria_, 119.
Amino-acids, formation of, by algæ, 108.
Amino-compounds, decomposition of, by fungi, 136, 138.
Ammonia, assimilation of, by bacteria, 33, 40, 45; effect of partial
sterilisation on soil content of, 66; formation in soil, 170;
formation in soil by bacteria, 32 _sqq._; formation in soil by fungi,
135 _sqq._, 141; influence of physical conditions on formation of,
137; property of attracting Diptera, 159; utilisation by higher
plants, 36.
Ammonium sulphate, effect on fungi, 121, 126, 127.
_Anabæna_, 102, 112.
_Annelida_, 149.
Antagonism of salts in soil, 60.
Ants, 153.
_Arachnida_, 150, 151.
Arctic soil, bacterial flora of, 24.
_Areinida_, 150, 151, 157.
_Armillaria_, 132.
_Ascomycetes_, 119.
_Aspergillaceæ_, 136.
_Aspergillus_, 119, 120, 135, 136, 138, 139.
Azotobacter, 6, 41, 95, 96; assimilation of nitrates by, 45;
decreasing efficiency in liquid culture, 44; indicator of soil
acidity, 44.
BACILLARIACEÆ, 100 (see also Diatom).
_Bacillus amylobacter_, distribution of, 24.
_Bacillus radicicola_, 24, 46 _sqq._; inoculation of soil with, 50;
life cycle of, 47.
Bacteria, association with algæ in nitrogen fixation, 111; anærobic
respiration of, 37; effect of arsenic on, 61; cellulose destroying,
134; changes in morphology in culture, 22, 47; classification of main
groups, 23, 25; composition of cells of, 39; inverse relationship
with protozoa, 10, 79, 82 _sqq._; isolation from soil, 21; methods
of describing, 21; method of estimating numbers of, 53 _sqq._, 80;
nitrogen fixation by, 110, 111; numbers in relation to algæ, 110;
numbers in soil, 52 _sqq._; oxidation of hydrogen by, 27, 37; effect
of partial sterilisation on, 8, 9, 66, 67; part played in soil
fertility by, 7; pure cultures, isolation by plating, 20; seasonal
changes in numbers of, 59, 87 _sqq._; effect of salts on, 60; short
time changes in numbers of, 11, 57, 58; effect of temperature on, 67;
uneven distribution of, 57.
_Basidiomycetes_, 119, 123, 132.
Beets, attacked by _Phoma betæ_, 135.
_Boletus_, 132.
_Botrytis_, 122.
Bryophyta, 100, 132.
_Bumilleria_, 105.
CALCIUM compounds in soil and fungi, 139.
_Carabidæ_, 150.
Carbohydrates, decomposition by bacteria, 26 _sqq._; decomposition by
fungi, 140; decomposition in soil, 168; effect on ammonia production
in soil, 33; presence in algal sheath and bacteria, 111.
Carbon, changes in amount in soil, 167; relationships of bacteria,
27; relationships of fungi, 133; source of, for soil bacteria, 39;
sources of, for soil fungi, 139.
Carbon dioxide, assimilation by algæ, 99, 107, 108; assimilation by
soil bacteria, 35, 36, 40.
Carotin, in algæ, 100; formed by _Spirochæta cytophaga_, 29.
_Cecidomyidæ_, 155.
Cellulose, decomposition by bacteria, 27, _sqq._; decomposition by
fungi, 133, 134, 141; relation of nitrogen supply to decomposition
of, 30; decomposition in soil, 168; as source of energy for nitrogen
fixation, 43.
Centipedes, see _Chilopoda_.
_Cephalosporium_, 120.
_Cephalothecium_, 136.
_Chilopoda_, 157.
_Chironomidæ_, 155.
_Chlorella_, 108.
_Chlorococcum_, 105.
_Chlorophyceæ_, 100.
Chlorophyll, loss of, from algæ, 108.
Ciliates, classification of, 72; cyst wall of, 73.
Citric acid, formation of, by fungi, 139.
_Cladosporium_, 119.
Clamp connections in fungi, 119.
Classification, of algæ, 100; of bacteria, 23, 25; of fungi, 131; of
protozoa, 69 _sqq._
Climate, effect of, on algæ, 101.
_Clostridium_, 41, 44; as fixer of nitrogen, 6.
_Coccomyxa_, 104.
_Coleoptera_, 150, 154, 155.
_Collembola_, 150, 153, 154.
_Colletotrichum_, 131.
Commensals, 132.
_Conjugatæ_, 100.
_Cortinarius_, 132.
Cotton, destroyed by fungi, 134.
Counting, of algæ, 109; of bacteria, 53 _sqq._; of fungi, 122; of
protozoa, 77, 79, 80.
Cresol, decomposition of, by bacteria, 22, 24, 31.
Criteria, physiological, of fungi, 128.
Crop growth, effect on fungi, 122.
_Cryptomonadineæ_, 100.
Cucumber leaf spot, 131.
Cyanamide, decomposition of, by fungi, 136.
_Cyanophyceæ_, 103 (see also _Myxophyceæ_ and blue-green algæ).
_Cylindrospermum_, 102.
Cysts, 68, 73, 74.
DENITRIFICATION, by bacteria, 37; by fungi, 136.
Desiccation, resistance to, by algæ, 106.
Dew, relation to algæ, 101, 113.
Diatoms, 104 _sqq._ (see also _Bacillariaceæ_).
Dicyanamide, decomposition of, by fungi, 136.
Dipeptides, formation of, by algæ, 108.
_Diplopoda_, 157.
_Diptera_, 150, 154, 155, 159.
Disaccharides and fungi, 134.
EARTHWORMS, abundance of, in soil, 153; effect of, in soil, 13, 160,
175.
Eel-worms, 149 (see also _Nematoda_).
_Elaphomyces_, 132.
_Enchytræidæ_, 149.
Energy, laws of, 165; relationships of soils, 166; requirements of
soil organisms, 15, 16.
Energy supply, relation of bacterial activities to, 25 _sqq._, 40,
44; sources of, for soil bacteria, 26 _sqq._, 40, 43; supplies of,
for soil organisms, 111, 164, 167, 168.
Environmental conditions in soil, 16.
Eremacausis, 2.
Ericales, 132, 135.
_Euglena_, 99.
_Euglenaceæ_, 100.
Experimental error, in bacterial counts, 54; in fungal counts, 124.
FARMYARD manure, see Manure.
Fats, used by fungi, 134.
Fatty acids used by fungi, 134.
Fertility of soil, views on, 2; effect of decomposition of plant
residues on, 1, 165; effect of organisms on, 175.
Filter paper, destruction of, by fungi, 133; destruction of, by
_Spirochæta cytophaga_, 28.
Fixation of nitrogen, discovery of, by Berthelot, 5; by bacteria, 40
_sqq._; by algæ, 110, 111; by mixtures of bacteria and algæ, 111; by
fungi, 135 _sqq._ (see also Nitrogen Fixation).
_Flagellatæ_, 100.
Flax sickness and fungi, 122.
Formaldehyde, as agent for destroying fungi, 141.
Fungi, control of, in soil, 139 _sqq._; counting of, 122;
distribution of, in soil, 119 _sqq._, 127; fertilisers, effect of, on
numbers of in soil, 126; as facultative parasites, 131, 132; fruiting
bodies of, 123; destruction of hemicelluloses by, 133; individual,
122, 123; action on monosaccharides of, 134; mineral relationships
of, 139; mycorrhizal, 132, 135, 139, 140; heterocyclic nitrogen
compounds and, 138; occurrence in soil, 118; qualitative study of,
118; selective feeding of, 140; specific determination of, 119.
_Fungi imperfecti_, 119.
_Fusaria_, 134.
_Fusarium_, 119, 120, 122, 128, 133, 136.
_Gamascidæ_, 156.
Gases of swamp water (Paddy soils), 113.
_Gastrodia_, 132.
Gelatinous envelope of algæ, 109, 111.
Geographical distribution of azotobacter, 41; of soil bacteria, 24;
of protozoa, 75, 76; of soil fungi, 119, 125.
Germination, of algal spores, 107.
Glucose, use of, by algae, 108, 109, 111; use of, by moss protonema,
109.
Glycocoll, formation of, by algæ, 108.
_Granulobacter_, 42.
Greenland, bacteria in soil from, 24.
“Grunlandmoor,” fungi in, 126.
_Hantzschia_, 105.
_Hemiptera_, 154.
_Heterokontæ_, 100.
“Hochmoor,” fungi in, 126.
_Hormidium_, 104.
Humus, the food of plants, 1; formation of, by fungi, 134, 141;
formation of, in soil, 168; forest, 132; fungal hyphæ as constituent
of forest humus, 132.
Hydrogen ion concentration, in soil, 17; effect on fungi of, 124.
_Hymenoptera_, 150, 154.
_Insecta_, 150, 157.
Insects, numbers present in soil, 154.
Invertebrata, definition of, 147; method of investigating, 148;
groups represented, 149; distribution in the soil, 151; dominant
species and groups, 153; environmental factors of, 157; feeding
habits, 156; relation to agriculture, 160; relation to nitrogen
cycle, 161.
Iron compounds, oxidation by fungi, 139.
_Isopoda_, 150, 151.
_Leguminosæ_, association with bacteria, 46 _sqq._; enrichment of
ground by, 5.
_Lepidoptera_, 150, 154.
Life cycles, of bacteria, 22, 47; of protozoa, 72 _sqq._
Lime, effect on fungi in soil, 121, 126.
_Lyngbya_, 112.
MAGNESIUM compounds, effect on fungi, 139.
Manganese compounds, effect on bacteria, 61.
Manure, farmyard, effect on algæ, 109, 110; effect on numbers of
bacteria, 60; effect on numbers of fungi, 126; effect on numbers of
insects, 154, 155.
Manure, Artificial, effect on fungi, 127.
Manure, town stable, occurrence of disease organisms in, 132.
_Mastigophora_, classification of, 71; species of, 71.
Media, containing nitrates, chemical analysis of, 111; for counting
soil bacteria, 54; for counting protozoa, 79; for counting fungi,
119, 123.
_Melanconium_, 134.
_Melolontha_, 150.
Methane, oxidation of, by bacteria, 26, 27.
Millipedes, see _Diplopoda_.
Mites, see _Acarina_.
_Mollusca_, 149, 157.
_Moniliaceæ_, 136.
_Mucor_, 120, 121, 136, 138.
_Mucorales_, 121, 134.
_Mucorineæ_, 118.
_Mycetophilidæ_, 155.
Mycorrhiza, 132, 135, 139, 140.
_Myriapoda_, 150, 156.
_Myxophyceæ_, 100 (see also _Cyanophyceæ_ and blue-green algæ).
NAPHTHALENE, decomposition of, by bacteria, 31.
_Naviculoideæ_, 100.
_Nematoda_, 149, 151, 157.
Nitrate, assimilation by algæ, 105, 108, 111; assimilation by
bacteria, 33, 40, 44, 51; assimilation by fungi, 136, 138; removal
from soil, 12, 112, 171; variations in amount in soil, 11.
Nitre-beds, 1.
Nitrification, and bacteria, 34; chemical changes in, 171; and fungi,
136; energy supply in, 35; mechanism of, 1, 3; and soil fertility, 1,
3.
Nitrites and fungi, 136; formation by bacteria, 34.
_Nitrobacter_, 35.
Nitrogen, changes in amount in soil, 167; cycle in soil, 161;
fixation by bacteria, 6, 40 _sqq._; fixation by fungi, 135, 136, 141;
fixation of, in clover plant, 5; increase by protozoa of fixation
of, 94, 95 (fig.); fixation sources of energy for, 43, 49; gain of,
in soil, 174; in invertebrates, 162; loss of, by leaching, 112;
loss of, from cultivated soils, 173; relationships of fungi, 135;
relationships of algæ, 110-112; relationships of bacteria, 32 _sqq._,
40 _sqq._; relationships of insects, 162.
_Nitrosococcus_, 35.
_Nitrosomonas_, 35.
Nodule Organism of the Leguminosæ, 6, 46 _sqq._
_Nostocaceæ_, 100, 101, 102, 107.
_Oligochæta_, 149, 151, 153, 157.
_Oospora_, 120.
_Orcheomyces_, 132.
Orchid cultivation and fungi, 132, 140.
_Orthoptera_, 154.
_Oscillatoriaceæ_, 100, 102.
Osmotic pressure, influencing effect of salts on bacteria, 50.
Oxalic acid, formation of, by fungi, 139.
Oxidations effected by soil organisms; by bacteria, 26 _et seq._; by
fungi, 139.
Oxygen, absorption by soils, 4.
PARTIAL sterilisation of soil, 8, 66 _sqq._, 96, 178; influence of
organic antiseptics, 177; limiting factor in, 67, 68.
Pectin, effect of, on fungi, 134.
_Pedras negras_, 112.
_Penicillia_, 134.
Pentosans, effect of, on fungi, 134.
Peptones, decomposition of, by fungi, 136, 138; source of nitrogen
for algæ, 108.
Periodicity, of protozoa in soil, 90 _sqq._ (fig.), 92 (fig.), 93.
Phenol, decomposition of, by bacteria, 24, 25, 31.
Phenylalanine, formation of, by algæ, 108.
_Phoma_, 132.
_Phormidium_, 106.
Phosphates, availability of, influenced by bacteria, 52; by fungi,
139; effect on bacteria, 46, 51, 60.
Photosynthesis, 99, 100, 107, 110, 113.
Phycocyanin, 100.
Physical conditions in soil, 16.
Physiological criteria, of bacteria, 22; of fungi, 128.
_Phycomycetes_, 119.
_Phytophthora_, 132.
Plant disease, and fungi, 139.
Plant residues, decomposition of, in soil, 168; influence of soil
reaction on, 165; relation to soil fertility, 1, 165.
Plasticity of fungi, 119.
_Plectonema_, 106.
Potassium salts, effect on bacteria, 60; influence of bacteria on the
availability of, 52.
Protein, decomposition of, in soil, 169; decomposition by bacteria,
32; decomposition by fungi, 138, 140.
_Protococcales_, 100.
_Protoderma viride_, 105.
Protonema of mosses, 100, 105, 106, 109.
Protophyta, chlorophyll-bearing, 100.
Protozoa, inoculation into soil of, 85 _sqq._; isolation from soil,
69; classification of, 69 _sqq._; life histories of, 72 _sqq._;
species of, in soil, 70 _sqq._; distribution of, in soil, 74 _sqq._;
retention of, by soil, 78 (fig.); size of, 90; reproductive rates,
93; inverse relation with bacteria, 79 _sqq._; presence of trophic
forms in soil, 9; numbers of, in soil, 90, 96, 97; fluctuations in
numbers of, 10, 81 (fig.), 82; external conditions, effect on, 82;
seasonal changes, effect on, 87 _sqq._; weight of, 90.
_Pteridophyta_, 132.
_Pythium_, 132.
REACTION of soil, 17.
Reaction of soil, effect on bacteria, 36, 37, 46, 48, 61; effect on
protozoa, 93, 94 (see also hydrogen ion concentration).
Relationships of Fungi, commensal, 132; mycorrhizal, 132; symbiotic,
132.
_Rhizopoda_; classification of, 70, 71; species of, 70, 71.
Rhythm, supposed in ammonification by fungi, 137.
_Rhizoctonia_, 132.
_Rhizopus_, 119, 120.
Rice plant, aeration of roots, 113; physiological disease of, 113.
Rock Phosphate as base for nitrifying organisms, 36.
Rothamsted, Broadbalk plot 2 (Farmyard Manure) algæ, 109; fungi, 125,
127; Insects, 152.
Rothamsted, Broadbalk plot 3 (Unmanured) algæ, 109; fungi, 120, 122,
127; Insects, 152.
Rothamsted, Broadbalk Plots 10, 11, and 13; 122, 127.
Rothamsted, Barnfield Plot 1-0 (Farmyard Manure), Protozoa, 80.
Rothamsted, unmanured grass plot, 120.
_Russula_, 132.
Rusts, 119.
_Saccharomyces_, 120.
Saprophytes, facultative, 131.
Saprophytism and algæ, 108, 110.
_Scenedesmus_, 108.
Seasonal fluctuations in numbers of soil organisms, 12, 87 _et seq._,
125.
Selective media, use of, in isolation of soil bacteria, 21.
Serological tests, separation of varieties of _B. radicicola_ by, 48.
Slugs, see _Mollusca_.
Smuts, 119.
Snails, see _Mollusca_.
Soil; comparison of, by volume, 17; effect of depth below surface
on algæ, 101, 104, 109, 110, 113; effect of depth below surface on
insects, 151; effect of depth below surface on fungi, 121, 126, 127;
effect of various treatments on fungi, 126, 127, 132; environmental
factors in, 16; inoculation of, for leguminous plants, 50; moisture
(see Water supply); population, control of, 177 _sqq._; population,
methods of investigation, 10, 15; sterilisation and fungi, 137, 138,
141 (see Partial Sterilisation); stored, survival of algæ in, 107;
type and fungi, 121, 126, 127.
Soil conditions, effect on bacteria, 33, 36, 37, 40, 46, 48, 50, 59
_sqq._; effect on protozoa, 82.
Soil fertility, see Fertility of soil.
_Spicaria_, 120.
Spiders, see _Areinida_.
_Spirochæta cytophaga_, 28, 43.
Spore forming bacteria in soil, 23, 34.
Spore, fungus, inhibition of formation, 123; presence in air of, 118.
Standardisation of cultural methods for soil bacteria, 54 _sqq._
Starch, decomposition of, by fungi, 134.
_Stichococcus_, 108.
Straw; effect on nitrate production in soil, 33; manure, 29; rotting
of, 30.
Sulphur oxidation, by bacteria, 37; by fungi, 139.
Symbiosis, of Azotobacter with other organisms, 42, 43, see also
Mycorrhiza and Nodule organism.
_Symphyla_, 150, 151, 157.
_Symploca_, 112.
_Tachinidæ_, 150.
Tannins, used by fungi, 134.
Temperature of soil and fungi, 127, 140.
Termites, 160.
_Testacella_, 149.
_Thiospirillum_, 37.
_Thysanura_, 154.
_Thysanoptera_, 154.
_Tipula_, 150.
Toluene, decomposition by soil bacteria, 31.
_Tolypothrix_, 112.
_Trichoderma_, 119, 120, 122, 134.
_Trochiscia_, 105.
Tropisms, 157.
_Ulothrix_, 105.
_Ulotrichales_, 100.
Urea, by fungi, 136, 138.
Uric acid, utilisation of, by fungi, 138.
_Vaucheria_, 104, 106.
Vitality, retention of, by algæ and moss protonema, 105, 107.
WATER; supply in soil, 17; and algæ, 112; bacteria, 50, 61, 82;
fungi, 127; protozoa, 82.
Wireworms, 155.
Wood, decay of, 134.
Woodlice, 150; (see also _Isopoda_).
YEASTS, 138.
_Zygnema_, 104.
_Zygorrhynchus mœlleri_, 119, 120, 121.
PRINTED IN GREAT BRITAIN BY THE UNIVERSITY PRESS, ABERDEEN
Transcriber’s Notes
Inconsistent and archaic or unusual spelling, capitalisation,
italicisation, hyphenation, etc. have been retained, unless mentioned
below. The names and classifications of the organisms as used in the
book do not always conform to modern names and classifications; these
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Page 14, table, lower right hand cell: the data given add up to 8,
not to 9.
Page 47, ·9 × ·18 in size: the source document does not include the
units; presumably the sizes are in microns.
Page 118, endnote 8c (2×): this note does not exist.
Subject Index, entry Zygorrhynchus mœlleri: also refers to
Zygorrhynchus vuilleminii.
Changes made:
Footnotes, tables and illustrations have been moved out of text
paragraphs; some tables have been split or re-arranged.
Several minor obvious typographical, punctuation and spelling errors
(including accents) have been corrected silently. In several cases
spelling differences (mainly of proper names) between the text and
the index and endnotes have been standardised. In the indexes and in
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text. Some page references have been corrected to indicate the
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or split to fit the available width.
Page 28, 29: MacBeth changed to McBeth as elsewhere (in the Author
Index the entries MacBeth and McBeth have been merged).
Page 32, formula: 30 changed to 3O.
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Page 85: closing bracket deleted after ... Table VII. and Fig. 13.
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and 150,000.
Page 97: No creature lies or dies to itself, ... changed to No
creature lives or dies to itself, ...
Page 104: Danske Aerofile Alghe changed to Danske Aërofile Alger.
Page 114: Recherche sulla Malattia del Riso ... changed to Ricerche
sulla Malattia del Riso ....
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polymorphisme ....
Page 116: literature notes 38 (Robbins) and 48 (Schindler) changed to
33 and 34 respectively.
Page 120: Zygorrhynchus vuillemini changed to Zygorrhynchus
vuilleminii as elsewhere.
Page 126: references to Waksman[24] and [24_e_] changed to [25] and
[25_e_].
Page 129: ... preparée de la pres de Russum ... changed to ...
préparée de la terre humeuse du Spanderswoud, près de Bussum ....
Page 134: reference to Kohshi[24] changed to [34].
Page 143: Sämenbildung changed to Säurenbildung (entry 5);
Wurzelbranderregern im Baden changed to Wurzelbranderregern im Boden
(entry 11).
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... Umwandlung von Aminosäuren in Oxysäuren ....; ... Wirkungen der
Schimmelze ... changed to ... Wirkungen der Schimmelpilze ....;
Hydrogen-iron concentration changed to Hydrogen-ion concentration.
Page 145: Ztschr. f. Garungs. Physiol. changed to Ztschr. f.
Gärungsphysiol.
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gegen Hemicellulosen.
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Page 170: ... alphatic amino-acids ... changed to ... aliphatic
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