OSMOSIS? CAPILARY ACTION? ROOT PRESSURE?
Andrews K Fletcher
andrew.k.fletcher at naturesway.demon.co.uk
Sun Dec 13 03:55:57 EST 1998
How does water really circulate all living things?
GCSE Basic Physiology and water transport.
OSMOSIS ? CAPILLARY ACTION? ROOT PRESSURE?
"I have chosen to relate to the following text book because it is written by
a person who like myself is not entirely satisfied by the explanations put
forward in the relevant subjects".
Figure Cs results raise the questions; What is osmosis and how are its
qualities explained in the text books.
For the currently accepted view of osmosis and all other views on water
transport I will refer to one of the standard GCSE text books entitled GCSE
BIOLOGY, D.G. Mackean. ISBN 0-7195-4281-2 first published in 1986.
Page 34 fig 3 Diffusion gradient
Page 36 OSMOSIS
Osmosis is the special name used to describe the diffusion of water across a
membrane, from a dilute solution to a more concentrated solution. In biology
this usually means the diffusion of water into or out of cells Osmosis is
just one special kind of because it is only water molecules and their
movement we are considering. Figure 3 showed that molecules will diffuse
from a region where there are a lot of them to a region where they are fewer
in number; that is from a region of highly concentrated molecules to a
region of lower concentration. Pure water has the highest possible
concentration of water molecules; it is 100% water molecules, all of them
free to move.
Figure 9 shows a concentrated sugar solution, separated from a dilute
solution by a membrane, which allows water molecules to pass through. The
dilute solution, in effect contains more water molecules than the
concentrated solution. As a result of this difference in concentration,
water molecules will diffuse from the dilute to the concentrated solution.
The level of the concentrated solution will rise or, if it is confined to an
enclosed space, its pressure will increase. The membrane separating the two
solutions is often called selectively permeable or semi-permeable because it
appears as if water molecules can pass through it more easily than sugar
Osmosis then is the passage of water across a selectively permeable membrane
from a dilute solution to a concentrated solution.
This is all you need to know in order to understand the effects of osmosis
in living organisms, But a more complete explanation is given below.
ALTERNATIVE EXPLANATION FOR OSMOSIS
The current text book explanation for osmosis appears to have ignored the
effects of gravity on liquids. The constant pull of gravity acts differently
on concentrated solutions than dilute solutions i.e. The concentrated
solution is heavier than the dilute solution and will always settle at the
bottom of a reservoir or in this case a vessel.
To see this clearly, picture Fig 9 without the membrane; the result would be
that the concentrated solution would sink and the dilute solution would
rise. This effect will not stop because of the membrane. The concentrated
solution will still cause the dilute solution to rise as we have seen
earlier; and as the concentrated solution moves into the opposite side
containing the dilute solution, the dilute solution is dragged through the
membrane in a circular motion. For every action there must be a reaction. In
order to prove this point add a little dye to the sugar solution and watch
the exchange between the liquids.
"When the effect that gravity exerts on concentrated solutions is added to
the equation of water transport and osmosis, it gives us a very clear
understanding of the driving mechanisms involved".
Chapter 7 Transport in plants
The main force which draws water from the soil and through the plant is
caused by a process called transpiration. Water evaporates from the leaves
and causes a kind of suction which pulls water up the stem. The water
travels up the vessels in the vascular bundles and this flow of water is
called the transpiration stream. The water vapour passes by diffusion
through the air spaces in the mesophyll and out of the stomata. It is this
loss of water vapour from the leaves which is called transpiration. The cell
walls which are losing water in this way replace it by drawing water from
the nearest vein. Most of this water travels along the cell walls without
actually going inside the cells. Thousands of leaf cells are evaporating
water like this and drawing water to replace it from the xylem vessels in
the veins. As a result , water is pulled through the xylem vessels and up
the stem from the roots. This transpiration pull is strong enough to draw up
water 50 metres or more in trees.
Most of this water evaporates from the leaves; only a tiny fraction is
retained for photosynthesis and to maintain the turgor of the cells. The
advantage to the plant of this excessive evaporation is not clear.
A rapid water flow may be needed to obtain sufficient mineral salts, which
are in very dilute solution in the soil. Evaporation may also help to cool
the leaf when exposed to intense sunlight.
Against the first possibility it has to be pointed out that, in some cases,
an increased transpiration rate does not increase the uptake of minerals.
Many biologists regard transpiration as an inevitable consequence of
photosynthesis, in order to photosynthesise, a leaf has to take in carbon
dioxide from the air. The pathway that lets carbon dioxide in will also let
water vapour out whether the plant needs to lose water or not. In all
probability, plants have to maintain a careful balance between the optimum
intake of carbon dioxide and a damaging loss of water.
Humidity if the air is very humid, i.e. contains a great deal of water
vapour, it can accept very little more from the plants and so transpiration
slows down. In dry air, the diffusion of water vapour from the leaf to the
atmosphere will be rapid. ( " I will deal with this point later on because
it is very important and has implications for human health ") Air Movements:
In still air, the region round a transpiring leaf will become saturated with
water vapour so that no more can escape from the leaf. In these conditions,
transpiration slows down. In moving air the water vapour will be swept away
from the leaf as fast as it diffuses out. This will Speed up the
transpiration. Furthermore, when the sun shines on the leaves, they will
absorb heat as well as light. This warms them up and increases the rate of
Page 73 continued Water movement in the xylem
You may have learned in physics that you cannot draw water up by suction to
a height of more than about ten metres. Many trees are taller than this yet
they can draw up water effectively. The explanation offered is that, in long
vertical columns of water in very thin tubes, the attractive forces between
the water molecules are greater than the forces trying to separate them. So
in effect the transpiration stream is pulling up thin threads of water which
resist the tendency to break.
There are still problems however, it is likely that the water columns in
some of the vessels do have air breaks in them and yet the total water flow
is not affected. The evidence all points to the non-living xylem vessels as
the main route by which water passes from the soil to the leaves.
"This statement suggests that the long thin tubes of the tree ,are used for
water transport, which are none-living , therefore must represent the tubes
used in my experiments at Brixham."
In Experiment 8 on page 79 it is demonstrated that liquid may be forced up a
stem by root pressure from the root system. The usual explanation for this
is that the cell sap in the root hairs is more concentrated than the
soil water and so water enters by osmosis (see page 36). The water passes
from cell to cell by osmosis and is finally forced into the xylem vessels in
the centre of the root and up the stem.
This is rather an elaborate model from very little evidence. For example, a
gradient of falling osmotic potentials from the outside to the inside of a
root has not been demonstrated. However, there is some supporting evidence
for the movement of water as a result of root pressure.
root pressures of 1-2 atmospheres have been recorded, and these would
support columns of water 10 or 20 metres high. Some workers claim pressures
of up to eight atmospheres (i.e. 80 metres of water)
" A column of water 80 metres high would undoubtedly cause water pressures
of eight atmospheres at the roots. However It is very difficult to see how a
root could generate 8 atmospheres of pressure."
However, root pressure seems to occur mainly in the young herbaceous (i.e.
non-woody) plants or in woody plants early in the growing season and though
in many species it must contribute to water movements in the stem. The
observed rates of flow are too fast to be explained by root pressure alone.
Transport of salts
The liquid which travels in the xylem is not, in fact pure water. It is a
very dilute solution, containing from 0.1to1.0% dissolved solids, mostly
amino acids, other organic acids and mineral salts. The organic acids are
made in the roots; the mineral salts come from the soil. The faster the flow
in the transpiration stream, the more dilute is the xylem sap. Experimental
evidence suggests that salts are carried from the soil to the leaves mainly
in the xylem vessels.
Transport of food
The xylem sap is always a very dilute solution, but the Phloem sap may
contain up to 25 per cent of dissolved solids, The bulk of which consists of
sucrose and amino acids.
There is a good deal of evidence to support the view that sucrose amino
acids and may other substances are transported in the phloem. The movement
of water and salts in the xylem is always upwards, from the soil to the
leaf. But in the phloem the sap may be travelling up or down the stem. The
carbohydrates made in the leaf during photosynthesis are converted to
sucrose and carried out of the leaf to the stem. From here the sucrose may
pass upwards to growing buds and fruits or downwards to the roots and
storage organs. All parts of a plant which cannot photosynthesise will need
a supply of nutrients bought by the phloem. It is possible for substances to
be travelling upwards and downwards at the same time in the phloem.
"note the dual flow has been observed in experiments with concentrated
solution and water filled tubes."
Page 74 continued
There is no doubt that substances travel in the sieve tubes of the phloem
But the mechanism by which they are moved is not fully understood.
There are several theories, which attempt to explain how sucrose and other
solutes are transported in the phloem but none of them is entirely
Uptake of water and salts
The water tension developed in the vessels by a rapidly transpiring plant is
thought to be sufficient to draw water through the root from the soil. The
precise pathway taken by the water is the subject of some debate, but the
path of least resistance seems to be in or between the cell walls rather
than through the cells.
When transpiration is slow, e.g. at night time or just before bud burst in a
deciduous tree, then osmosis may play a more important part in the uptake of
One problem for this explanation is that it has not been possible to
demonstrate that there is an osmotic gradient across the root cortex which
could produce this flow of water from cell to cell. Nevertheless, root
pressure developed probably by osmosis can be shown to force water up the
root system and into the stem
The methods by which roots take up salts from the soil are not fully
understood. Some salts may be carried in with the water drawn up by
transpiration and pass mainly along the cell walls in the root cortex and
into the xylem.
It may be that diffusion from a relatively high concentration in the soil to
a lower concentration in the root cells accounts for uptake of some
individual salts. But it has been shown (a) that salts can be taken from the
soil even when their concentration is below that in the roots and (b) that
anything which interferes with respiration impairs the uptake of salts. This
suggests that active transport (p.35) plays an important part in the uptake
The thing that becomes clear from reading the established explanations for
water transport is that if it were a bucket, very little water would be
transported due to the large number of holes in it !
'A new scientific truth is not usually presented in a way to convince its
opponents. Rather, they die off, and a rising generation is familiarised
with the truth from the start.'
HTML COPY available which shows animated working models. If you would like a
copy, send me an email with your address details and contact information and
a brief note relating to your background and interest in this subject.
If I receive a lot of requests for this file, I will consider publishing it
on my web page. But would rather know who wants it and why.
The following review came from a letter I wrote to professor H T Hammel,
who is a powerful member of the Max Planck Institute.
SCHOOL OF MEDIICINE date September 6/ 1995
Dear Mr Fletcher:
I received the information you sent me regarding your ideas about fluid
transport in trees, in tubing and in the vascular system in humans.
I will study your ideas and comment upon them as soon as possible. A Quick
scan of your Brixham experiment prompts me to ask if you conducted this
experiment with boiled water without any solute added to the tubing on
either side of the central point which you raise 24 meters? I expect that
you could raise the tubing to the same height with or without solute in the
water. In any case , your experiment confirms that clean water (water that
is unbroken water, water that is without a single minute bubble of vapour)
can support tension of several hundreds of atmospheres. The record tension
obtained experimentally is 270 atmospheres. At 10 degrees C. (c.f. Briggs,
L. Limiting negative pressure of water. Journal of Applied Physics 21:
I expect even this tension at brake point can be exceeded by careful
cleansing of the water, to remove even the most minute region of gas phase.
When the water is already broken, as occurs when gas is entrapped on
particulate matter in ordinary water, the water will expand around even a
single break when tension (negative Pressure) is applied to the water. When
you boil the water, prior to applying (2.4-1) ATM negative pressure to the
water in the highest point of the tubing, you eliminate some of these breaks
in ordinary water. I expect that dissolving NaCl or other solutes in the
water will have little or no effect on the way you measure the tensile
strength of water.
I am enclosing some reprints that may interest you. Some of these deal with
negative pressures we have measured in tall trees, mangroves and desert
shrubs. Other reprints deal with how solutes alter water in aqueous
solutions and how colloidal solutes (proteins) affect the flux of protein
free fluid between plasma in capillaries and interstitial fluid.
Sincerely H.T. Hammel Ph.D.
Adjunct Professor of Physiology and Biophysics, Indiana University. Emeritus
Professor of Physiology, University of California, San Diego. Foreign
Scientific Member Max-Planck-Institut fur physiologische und Klinische,
cc: Professor Michel Cabanac, Laval University, Quebec
New Theory for Fluid Transport
Introduction: All life on earth developed with one thing in common; Earth!
The constant forces are gravity, and the energy from the sun. The most
abundant resources are minerals and water.
Plants and animals alike, all depend on the properties of water for
transporting minerals and nutrients. Because life is based on water, in
that everything alive started from a few drops, life must have evolved by
finding the easiest and most direct pathway, after all liquids are very good
at finding the most direct route possible. Yet, at first glance, everywhere
one looks life appears to have chosen the least likely of paths, if it is
trying to overcome the effects of gravity. Would trees, with species like
the giant Californian redwoods (sequoia sempervirens), towering over a
hundred metres high have chosen a vertical direction?
How then have plants and animals harnessed the constant pull of gravity in
order to thrive and grow?
On a summer day a large oak tree may take up a hundred gallons of water or
more, enriched with minerals and nutrients from the soil. At first glance
it is doing so against the pull of gravity, producing flow rates, which
cannot be explained or shown by working models based on osmosis, capillary
action or root pressure. So how are trees doing it?
Over 95% of the waters drawn in at the roots of a tree evaporate into the
surrounding air through the leaves by transpiration. The evaporated
moisture contains no minerals. However, the water remaining inside the tree
contains a variety of mineral salts dissolved from the soil, together with
sugars produced by the tree. The transpired water results in a
concentration of salts and sugars within the leaves. Concentrating a
liquid, (sap), which contains substances that are heavier than water, must
result in the production of a heavier solution than the pre-transpired
liquid. Because of the resulting imbalance in density the heavier solution
is drawn towards the base of the tree, due to the effect of gravity (maple
syrup, latex and amber are evidence for this). Downward flowing sap occurs
predominantly within the phloem vessels. When an excess of concentrated
liquid is produced during favourable weather conditions, the downward
flowing sap forms new tubes from the cambium, as it is forced down by
gravity, in a continual cycle of growth.
In hard woods, sap flows from cell to cell through openings or
perforations, in the membrane between abutting vessels.
In soft-woods, the sap flow controls movable valves, or pits - (thin
areas), in the walls of conducting tracheids. Concentrated pulses of sap
may eventually be found to be present in some xylem vessels, as gravity
inevitably finds the most direct route, with the least resistance, to the
But for every action there must always be a reaction, and the reaction in
this case is that the downward flowing liquid behaves exactly like a plunger
in a syringe. As it flows down it causes the entire contents of connected
tubes filled with the less dense liquid to be drawn up.
Here we have a simple power source, which is driven purely by evaporation,
posture and gravity.
The forces produced by this phenomenon are easy to demonstrate in simple
tubular experiments. The main forces are produced at the head and tail of
the falling solutions. The head produces a positive force, or pressure, and
the tail produces a negative pressure. I believe that the positive force
within the mineral laden sap is responsible for the formation of the tubular
structures found in timber. The positive force prevents tubes from closing.
As more sap flows through the same pathways, some of the sap is used to
strengthen the tubes which will eventually become strong enough to resist
the negative pressures. The tree transports the dilute solution of water
and minerals to the leaves using these tubes. Thereafter becoming what we
call the xylem vessels.
As the concentrated liquid falls towards the ground, minerals are locked
away as timber, while the mineral laden liquid arriving at the roots is
inevitably re-diluted by the dilute solution drawn from the soil. The
imbalance in the liquid is corrected as it becomes lighter or less dense
than the downward flowing sap and begins its journey back to the leaves,
where the process continues, providing the tree with a constant supply of
water and nutrients.
In the autumn / fall, when the leaves have fallen, the circulation is
altered as a greater positive pressure is exerted towards the roots, because
transpiration has ceased and therefore fluids flowing towards the top of the
tree would be compromised. At this time of the year root growth would be
As fluid channels begin to offer resistance, the sap must find alternative
routes. The new directions may be vertical or horizontal, but always in the
path of least resistance. Eventually tubes become redundant and new tubes
are formed. Fluids of different specific gravity have been observed to flow
in both directions, simultaneously while in the same tube. In fact this
'transpiring gravitational flow system' is able to operate without tubes and
has been attributed to causing the oceans to circulate (Atlantic conveyor
Early attempts at lifting water:
The story goes that the reigning Grand Duke of Tuscany had ordered a well to
be dug to supply the ducal palace with water. The workmen came upon water
at a depth of 40 feet, and the next step was to pump it up. A vacuum lift
pump was erected over the well, and a pipe let down to the water, but the
water was found to rise to a height of 33 feet and no more, in spite of the
most careful overhauling of the pump mechanism. It was at this stage that
Galileo was consulted. While the famous philosopher was unable to offer a
solution, he at least indicated the problem. Here above the 33 feet of
water was seven feet of vacuum. The limit for raising water by suction in a
tube appeared to be thirty-three feet.
Why should there be this limit when trees are observed to ignore it?
By introducing a loop of tubing, instead of a single tube, to simulate the
internal structure of plants and trees, and suspending it by the centre, the
problem of raising water above the 33 feet limit is solved!
The reason a loop of tubing succeeds where a single tube fails is because
the cohesive bond of water molecules is far stronger than the adhesive
qualities of water observed in Galileo's lift-pump problem. Using a loop of
tubing enables water molecules to bond to each other in an unbroken chain.
It helps to picture the unbroken loop of water as a cord instead of a
liquid, supported by a pulley in the centre with tension applied to both
The columns of water held in both sides of the tube exert a downward force
due to the weight of the water contained in the tube. This force causes the
water molecules in the tube to be stretched, causing the water to behave
like an elastic band. In order to demonstrate this affect on water molecules
I repeated the experiment shown in figure 1 without the added saline
solution, the two open ends of the tube at ground level were removed from
the demijohns, exposing them to the air.
Though the tube contained water, it did not flow from either side of the
tube. In fact the opposite effect was observed; the water level in both
sides of the tube immediately rose to a new level about half a metre from
the ends of the tube. Even more surprising the water columns stayed there
suspended by the cohesion between the water molecules.
In order to try to upset the balance I then blew up one side of the tube,
causing the water level on that side to rise. I then released the pressure
and the water returned to the same equal level. This observation offers an
exciting explanation to the problem of explaining why water does not pour
from the wound when a tree is felled.
However, the present laws of physics state that water cannot exist in its
liquid form below 4.6 torr, yet the water remains in the tube. Only when
the tube is lowered, or if a bubble appears at the top of the loop of tubing
does the water flow out from the open ends.
THE BRIXHAM CLIFF EXPERIMENT
This experiment successfully demonstrated fluid transport to a height, which
exceeds the current accepted limit of 10 metres and how this applies to the
way that trees draw water to their leaves.
48 metre single length of clear nylon tubing, 6.35 mm inside diameter x 9.5
mm outside diameter (type used to draw ales in the brewery trade), two clear
glass demijohns, a large tray, 50 mils of concentrated salt solution with
added red food dye, 50ml syringe minus the needle, sufficient degassed or
previously boiled and cooled water to fill the tubing, the demijohns, and
for adequate top ups. Adequate nylon cord to hoist the tubing and pulley to
the desired height, a small pulley and adhesive cello-tape.
The two demijohns were filled to the brim with the water and placed in a
suitable tray to catch any displaced water. The length of tubing was half
filled with the water by siphoning. This was achieved by submerging one end
of the tube in the water filled demijohn placed on a table. When the water
reached the centre of the loop, the open end of the tube was capped with a
thumb. The end of the tube in the demijohn was removed and the 50 mils of
coloured salt water was introduced via the large syringe. The demijohn was
then re-filled to the brim and the tube was re-submerged, making sure that
no bubbles were introduced by adjusting the height of the unfilled side of
the tube. By removing the thumb, the remaining length of tube was filled
and again capped, making sure that no air was trapped inside the tube. At
this point the demijohns were, refilled. The capped end of the tube was
then inserted into the other water filled demijohn and both ends secured at
an equal level, with cello-tape, again making sure that no air was allowed
to enter the tube.
A length of the nylon cord equal to that of the length of tubing used was
passed through the pulley, provided a safe ground level means to hoist the
loop of tubing to the desired height. The pulley and the main nylon cord
was hoisted to the desired height and secured at the top of the cliff on a
separate length of cord. Adhesive cello-tape was wrapped heavily around the
two sides of the loop of tubing 15cm from its centre to secure one knotted
end of the main nylon cord, which ran through the pulley for the purpose of
lifting the tube, taking care not to reduce the tubes diameter. The
cello-tape was used to bind the cord to the tube.
Coloured insulation tape was used to secure both sides of the tube together
providing an excellent ascent measurement when placed at one-metre
The centre of the tube was then gently hoisted, taking care to keep the
ascent as smooth as possible. As the tube was raised the salt solution
began to fall, due to the influence of gravity; this caused one of the
demijohns to start overflowing indicating a positive pressure, while the
second demijohn began to lose water at the same rate indicating a negative
pressure. The emptying demijohn received frequent top ups, until the salt
solution arrived at the overflowing demijohn and the flow stopped.
The fifty mils of salt solution caused the water in the tubes to circulate.
The amount of water displaced and collected in the tray represents
approximately the volume of water held in one side of the tube. Which meant
that the fifty mils of salt solution had lifted water from one demijohn to
the height of 24 metres and caused water many times its own weight and
volume to rise. (I have used as little as 10 mils of coloured salt solution
in the same experiment with a slower rate of decent but with similar
displacements of water). Initially the experiments were tested at lower
levels of elevation. 24 metres vertical lift was achieved when demonstrating
the phenomenon before an audience of journalists and Forestry Commission
scientists at the Overgang cliff, Brixham, July 1995.
For the purpose of demonstrating this phenomenon use a scaled down two metre
high version of Fig 1. Substituting the demijohns for small narrow necked
bottles. The type of tubing used to oxygenate aquariums is ideal for this
purpose. A two-mil syringe minus needle, filled with coloured salt
solution, connected to a T piece via a short length of tube, may be added
close to the centre of the elevated tube to introduce salt solution
intermittently while the tube is elevated, providing multiple
demonstrations. Furthermore, the tube used in the salt free side of the
experiment, (return side), may be of a larger bore size. Soft wall,
silicon tubing shows visible signs of distortion when the saline solution is
allowed to flow through it. The side containing the saline solution expands
while the other side contracts, again indicating the presence of both
positive and negative, pressures.
The experiments shown have been repeated using a variety of substitutes for
salt solution, such as strong tea solution, fruit juices and milk etc. in
order to relate directly to plants and animals. The flow rates achieved
using different solutions, produced different rates of flow.
Umbrella Plant Experiment, (cyperus )
In order to demonstrate that liquids of higher concentrations move through
plants in relation to the constant pull of gravity. Take a freshly cut stem
about 15cm long, with leaves intact, from an umbrella plant. Place the
cutting upside down, in a glass container of water. After several weeks the
umbrella plant starts to grow roots from what was the top of the plant and
new stems are produced, as the shoots grow vertically in the normal way.
The liquid processes involved within the plant for both root and leaf
production, must have travelled from one end of the cut stem to the other.
Indicating that gravity has an important influence.
When relating back to trees, the negative pressure, observed in the demijohn
with the falling water level, provides us with a clear understanding of the
mechanisms involved in drawing water through the roots from the soil. The
positive pressures caused by the weight of the column of water held in the
tree, plus the additional influence of gravity acting on the concentrated
solutions, induced by the loss of moisture at the leaf, provides the roots
with sufficient power to penetrate the earth.
Explanation for fluid exuding from a cut stem.
To demonstrate this effect, fill a vertically held open ended u tube with
water, Fig 2A, and add a little coloured concentrated salt solution to one
side, Fig 2B, the level of the salt solution will drop causing the opposite
side to overflow. Imagine the loop of tubing is one of many tubes in the
stem of a freshly cut plant or tree with roots in the soil. The overflowing
water represents the xylem sap rising under the influence of the positive
pressure, generated by gravity acting upon the concentrated sap in the
This is an important observation that gives a clear understanding of why
plants and trees continue to grow upwards.
Little or no cross contamination takes place between liquids in the
clean-water-side and the coloured saline side of the tube. Fig 2 C, I have
left this experiment suspended for five days and it appears to remain
stable. Circulation within an enclosed system, Fig 3, eliminates siphon as
an explanation, demonstrating that flow occurs inside and would continue to
do so if the tube was pressurised.
The thin columns of water in trees are known to brake, making a cracking
sound through a stethoscope. Cavitation occurs immediately the bead of water
separates. The formation of gas at the uppermost part of the raised loop of
tubing, Fig 1, caused both columns of water to fall towards the ground and
form a new level of 33 feet. The space above the water columns is a vacuum.
The circulation in trees continues, despite continuous cavitations, which
means that they are able to refill or repair the vacuum. The internal part
of a tree is a network of veins, or tubes, most of which run vertically.
However some tubes run at an angle and some horizontally and provide links
to other tubes, which interconnect at random levels. The internal tubular
parts of the tree are themselves captivated inside a large tube, which is of
course the bark or outer skin.
Water columns within the internal tubes of a tree, are continually stressed
under a negative pressure, caused by downward flowing concentrated solutions
within the trunk and branches. Cavitation occurs because the long thin
columns of water are pulled apart. Immediately the cavitation forms, the
internal pressures of that tube switch from a negative pressure to a
positive pressure, forcing the more dilute solution in the opposing side of
adjoined tubes upwards, Fig 2.B. & Fig 2 C. The downward force causes an
increase in the head of water at the top of the tube. It is this increase in
the head of water that gives a tree both momentum and direction to follow in
its cyclical growth. Furthermore an increase in the positive pressure above
the cavitation refills and repairs the vacuum, therefore enabling the tree
to continue with water transport, and allowing gas bubbles to percolate
upwards and out through the leaves.
This ability of the tree to switch from positive pressure to negative
pressure and visa-versa gives us an understanding of the pressures observed
in the roots of the tree. The roots being able to drive down through the
earth under a positive pressure and expanding forces yet are still able to
suck in water under a negative pressure.
* Students conducting any overhead experiments must observe the same Hard
Hat safety regulations imposed on building workers.
* Experiments involving tube elevations higher than classroom levels should
always be supervised. The safest area for this kind of experiment to take
place is on a spiral staircase. Cliff top experiments are dangerous.
* A nylon line passed through a small pulley block, which has been secured
at the desired height, enables the loop of tube to be elevated safely from
* Boiling water is dangerous and should not be handled or moved until it has
cooled sufficiently enough to prevent scalding.
A simple thought experiment
This thought experiment is designed to clarify the direction and momentum of
fluids as they are pulled and pushed through the body by the magnetic or
attractive force of gravity.
Red represents both high levels of oxygen and concentrated solutions caused
by the loss of moisture during the evaporative processes which occur in
bodily functions. The alterations in specific gravity which occur in the
fluids close to the surface lining of the lungs, respiratory tract and skin,
could well be responsible for providing the dissolved oxygen, which we
require, with sufficient force to enter the circulatory system.
Blue represents both low oxygen and a reduction in specific gravity, due to
the loss of spent salts in the excreted urine, which is shown as yellow in
the drawing. The increase in more dilute fluids from the stomach and
intestines, is also anaerobic (containing no oxygen) producing methane as a
by-product. Therefore the liquids entering the system from our diet would
contain no oxygen, which would undoubtedly cause any blood which passes
through to show a significant reduction in oxygen.
Now apply the principles of pressures generated by the tiny pulses of
concentrated solutions as they travel through the various tubes of the
thought diagram. Personally I find that this simple drawing helps to keep
my mind focused sharply on the holistic processes involved in all living
things, be they plants or people. Strangely enough there is a similar
drawing in most physiology books, which shows the direction of the
Judge for yourself by looking at both drawings which
way the fluid's flow and how they are driven. As I have said earlier the
only way to gain a good understanding of science is to form your own
opinions, based on all the evidence you can lay your hands on. If for
instance you see an experiment in a paper or a textbook, including this one,
providing the experiment is not going to cost you a fortune, set it up. But
then you must also try to find an alternative explanation for the processes
that you witness.
Urine for instance was used to determine whether fluid transport could be
taking place in humans and animals, In a similar process. For example
respiration causes water to evaporate from the lungs and respiratory tract.
Fluids remaining in the body contain minerals and must therefore be
concentrated. Gravity causes the heavy solution to be drawn back through the
lining of the lungs and respiratory tract and down through the vessels in
the body, carrying dissolved oxygen with it.
Concentrated solutions arrive at the bladder via the kidneys where they are
excreted in the urine. However the kidneys are not 100% efficient and some
minerals arrive in the lowest anatomical extremities, solidifying as finger
and toenails or horses hooves etc. Clippings of which sink when dropped into
Andrew K Fletcher Page 1 15/04/98
Summer Haze, 26 Berry Drive, Paignton, Devon, TQ3 3QW, UK.
Dr David Cutler of The Jodrel Laboratory at Kew Gardens is curently helping
me to write a paper on this subject in a way that it might be published in a
journal. I could sure use some more help and would appreciate offers of
Andrews News wrote in message
<913461890.7789.0.nnrp-05.d4e44203 at news.demon.co.uk>...
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