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What Is So Important About Blood?

 

In Hebrews 9:22 the Apostle Paul made a startling statement. “And almost all things are by the law purged with blood, and without shedding of blood is no remission.” (1)

remission (Strong 8592 (2)) = aphesis, “a release from bondage, imprisonment, liberation from captivity, and remission of debt.”

This remission, used as a noun, is further described by Christ in Luke 4:18 as follows:

“The spirit of the Lord is upon Me, because He has anointed Me to preach the gospel to the poor; He has sent Me to heal the brokenhearted, to preach deliverance to the captives, and recovering of sight to the blind, to set at liberty [aphesis] them that are bruised.”

Several references also make clear that aphesis means the forgiveness or pardon of sins, letting them go as if they had never been committed, and a total removal of sin’s penalty (Matthew 26:28; Ephesians 1:7).

The Real Issue Is Sin and Death

Alright, blood purges almost all things, including sin. So, what is the real issue here? Is it not the fact that sin — the breaking of God’s laws (I John 3:4) — leads to death (Romans 5:12-14)? We are not speaking of just a physical death, for Adam and Eve were promised that penalty upon their breaking God’s warnings and becoming a law unto themselves — “But of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat thereof you shall surely die” (Genesis 2:17) — but we are also speaking of eternal death, a total expunging of one’s self by the great God who created the person: “The soul that sins, it shall die” (Ezekiel 18:4, 20), unless the penalty is paid for that sin in some way so sin is no longer imputed to the offender.

In other words, sin leads to death, eternal death, a total wiping away of the offending person unless some process steps in to prevent it. We as Christians know that the process involves the shed blood of Jesus Christ the Perfect One, Son of God, Emmanuel, Healer, and Sustainer. May we thus say that the real issue with blood is that if that blood is from a perfect sacrifice it wipes away the sins of the offender forever, and permits life eternal? is not the big issue sheer existence itself, OF being … the “i am”, as it were?

God is a God of life. Without life there is nothing … no comprehension of what is, no sensing of the sights, and sounds, tastes, smells, touch, and the thoughts that process these objects of our senses. Without existence there is nothing, and it is God’s very nature to live, to exist, and to be … forever and ever. He could confidently state that He was the “I AM” to Moses at the burning bush in the shadow of Mt. Sinai (Exodus 3:14). That comprehensive identity He wants to extend to all of the saints, and will indeed during the course of time.

I AM (Strong 1961 (3)) = hayah, “To become, occur, come to pass, be.” According to J.R. Kohlenberger, III, in The New Strong’s Expanded Exhaustive Concordance of the Bible, the use of “hayah hayah” (i am that i am] in Exodus 3:14 is more than a mere statement of identity, but a declaration of divine control of all things. It also must imply His eternal existence through the ages: past, present, and future.

You cannot imagine existence apart from your own. Neither can God Himself, who made you in His express image (Genesis 1:27). He is forever, and He wants us to be as well, so through the formula of shed blood of His son Jesus Christ to remove our sins we are able to follow in Christ’s footsteps and become like Him, servants of our Father forever (I John 2:6; Revelation 1:5-6; John 17:2; Romans 2:7; Hebrews 9:15).

Blood — What Is It?

If there is no remission of sin without the shedding of blood, then blood must necessarily possess some remarkable qualities. The Scriptures indicate that “life is in the blood” in several places: Genesis 9:4, Leviticus 17:11 and 14, and 19:16, Deuteronomy 12:23, and Matthew 27:4 and 24. Look at Leviticus 17:11:

“For the life of the flesh is in the blood; and I have given it to you upon the alter to make an atonement for your souls, for it is the blood that makes an atonement for the soul.”

We know that the blood of bulls and goats cannot truly atone for man’s sins (Hebrews 9:11-14), and that animal sacrifices were merely a type of the ultimate crucifixion and spilling of blood of the Redeemer. How, then, does blood fulfill such a marvelous picture of salvation from sin’s penalty?

Blood gives life! It grants life to the entire body, to the 10 trillion cells that comprise its many tissues and organs. Blood accounts for about 8% of the adult body’s weight, with males having 5 to 6 quarts and females about 4 to 5 quarts. (4) It has a temperature of 98.6 F (38 C), and a pH of 7.35 to 7.45, maintained within a narrow range to keep the body slightly alkaline. If that pH range is compromised, illness results. Whole blood is 4.5 to 5.5 more viscous that water. It is red in color when oxygenated (in arteries) and turns more blue in color when depleted of oxygen (in veins). (5)

To grant life to the body’s trillions of cells, it must reach every last one of them on a continual basis, and perform the following three major functions (6):

A. Transport

      1. Transport of oxygen (O2) and carbon dioxide (CO2) between the lungs and the cells
      2. Transport of nutrients from the digestive tract and storage sites (liver, fat, etc.) to the body’s cells
      3. Movement of waste products from cells to be detoxified and removed by the liver, kidneys, and skin
      4. Distribution of hormones from glands where they are produced (pituitary, thyroid, pancreas, etc.) to target cells where they act
      5. Move heat generated by cellular oxidation to the skin to regulate body temperature

B. Protection

      1. White blood cells (leucocytes) destroy invading microorganisms and cancer cells.
      2. Antibodies and other proteins destroy pathogens.
      3. Platelets initiate blood clotting and minimize blood loss.

C. Regulation

      1. Adjustment of pH by interacting with acids and bases
      2. Regulation of water balance in cells by transferring water to and from them

All of these functions of blood are essential for the maintenance of life for each cell of the body. How the blood performs these tasks is miraculous indeed, and is carried out by a complex of plasma — the clear fluid that carries the cells and other components — and the “formed elements” having a cell membrane and a definite shape, including red blood cells, white blood cells, and platelets.

Blood Plasma

The plasma is mostly water that contains dissolved proteins, enzymes, nutrients, wastes, hormones, and gases. Proteins are the most abundant of all substances in plasma. Cells called macrophages in the liver, intestines, lungs, and lymph system can break down these proteins to release amino acids for building cells and tissues. The proteins also act as carriers for small molecules which are transported to cells than need them. They also help stabilize body and blood pH by binding to excess H+ ions and removing them to maintain a pH of about 7.4. Plasma proteins help blood coagulate at sites of vessel injury to staunch the loss of blood, and prevent the invasion of foreign microorganisms. These proteins help maintain water balance of cells and blood through osmotic pressure effects. (7)

Individual plasma proteins include albumin, that are the smallest and most abundant molecules that maintain plasma water content, and help transport substances like hormones and fatty acids. Globulins include high and low density lipoproteins (HDL and LDL). HDL functions in lipid (fat) transport to cells for energy metabolism, membrane construction, and hormone operation, while LDL is involved in cholesterol and steroid utilization. Fibrinogen, yet another plasma protein, is a precursor to the sticky fibrin that creates the framework of blood clots. (8)

Also in blood plasma are found amino acids that come from digested proteins in the intestines, or from degraded tissue proteins. Nitrogenous wastes from the breakdown of cells are removed by the kidneys, and various dissolved nutrients like glucose, fats, amino acids, cholesterol, vitamins, minerals, and others are transported to the cells for growth and metabolism. Gases like oxygen, carbon dioxide, and nitrogen are transported by the plasma to and from cells and electrolyzes, like sodium and potassium ions, maintain the osmotic potential of cell cytoplasm.(9)

Red Blood Cells

The red blood cells (erythrocytes) are the most numerous of the blood cells, and function to pick up oxygen from the lungs and transport it to cells, as well as to pick up carbon dioxide from cells and unload it in the lungs. These amazing cells are disc-shaped with a thick rim and a thin, sunken center. Various glycoproteins and glycolipids on the cell membranes determine one’s blood type. These membranes contain spectrin and actin, two proteins that give the cells resilience and durability, allowing them to stretch, bend, fold, and squeeze through the labyrinth of tiny blood capillaries to reach even the remotest cells in the body, and then spring back to their original shape. (10)

Red blood cells cannot consume oxygen because they contain no mitochondria, so all of the oxygen they absorb in the lungs is carried to the body’s cells. The mitochondria and nucleus are both lost, so the cells cannot repair themselves, and thus survive only an average of 120 days. However, because they have fewer cellular parts they are flat and have a large surface area to volume ratio, so oxygen and carbon dioxide diffuses quickly into and out of them. About a third of the cytoplasm of these red blood cells is hemoglobin, the compound that binds oxygen and some carbon dioxide, and gives it its red color. Old cells become increasingly fragile and eventually become trapped in the spleen, where they are degraded, leaving only membranes that are digested by macrophage cells in the liver and spleen. The hemoglobin is either recycled into new cells or degraded. (11)

White Blood Cells

White blood cells, also called leucocytes, can be divided into granulocytes, which contain colored granules, and agranulocytes, which do not. Granulocytes include neutrophils, which destroy bacteria and release compounds that kill or inhibit the growth of bacteria, eosinophils, that destroy allergens and inflammatory compounds and also release enzymes that disable parasites, and basophils. Basophils secrete histamine that increases blood flow to tissues, and release heparin, an anticoagulant that promotes the mobility of other white blood cells by preventing clotting. (12)

Agranulocytes are of two main groups, the lymphocytes and the monocytes. Lymphocytes destroy cancer cells, cells infected with viruses, and invading foreign cells. In addition, they create antigens that activate other cells of the immune system, coordinate actions of other immune cells, secrete antibodies, and help “immune memory”. Monocytes, the largest cells of all in the blood, change into macrophages which digest pathogens, dead neutrophils, and dead cell debris. They also secrete antigens to activate other immune cells. (13)

Platelets

These small fragments of bone marrow cells, but not cells themselves, play a big part in the clotting mechanism at wound sites. They form temporary plugs to stop bleeding, secrete procoagulants to promote blood clotting, and secrete vasoconstrictors which cause broken vessels to constrict. These platelets also dissolve blood clots that are no longer needed, they digest and destroy bacteria, and they secrete compounds that attract neutrophils and monocytes to sites of inflammation.

The mechanisms involved in stopping bleeding are very complex, and platelets are at the center of this process. Normally platelets do not adhere to the smooth, platelet-repelling surfaces of blood vessels, but when a vessel is broken the platelets extend long, spiny projections that adhere to the vessel walls and to other platelets. These projections then contract and draw the walls of the vessel together, and reduce or stop minor bleeding. Procoagulants which are secreted by the platelets help convert the plasma protein fibrinogen into fibrin, a sticky protein that adheres to the walls of the vessel and collects blood cells and platelets, forming a mass that helps to seal the blood vessel break. (14)

Production of Blood

Shortly after conception, during development of the embryonic child, blood cells are produced in the yolk sac. As the child grows, the bone marrow, liver, spleen, and thymus gland produce blood cells, but at birth the liver stops producing them. Shortly after birth the spleen stops producing all but lymphocytes, which it continues to generate for life. From infancy onwards all of the cells are produced in the red bone marrow, while lymphocytes (white blood cells) are also produced in lymph tissue as well as in the thymus, tonsils, lymph nodes, spleen, and in patches of lymph tissue in the intestines. (15)

The generation of red blood cells is a most interesting process. Certain bone marrow cells called proerythroblasts make contact with erythropoietin, a hormone that triggers the cell differentiation process. The resulting cells multiply and begin producing hemoglobin, the cell nucleus is discarded, and eventually the cells leave the bone marrow through the blood stream where they mature into erythrocytes (red blood cells).

White blood cells begin with certain cells called hemocytoblasts. These cells differentiate into three types called B progenitors (which become B lymphocytes), T progenitors (which become T lymphocytes) and granulocyte-macrophage colony-forming units (which become granulocytes and monocytes). These various cells have receptors that receive chemical messengers that direct them to produce a specific type of cell in response to the body’s need, such as the need to fight an infection or some other challenge to the body. Red bone marrow stores granulocytes and monocytes until needed, but leukocytes do not remain in the blood for very long. Granyulocytes circulate for only 4 to 8 hours and then migrate into tissues, where they live for another 4 to 5 days. Monocytes travel in the blood for 10 to 20 hours, and then migrate into tissues where they transform into a variety of macrophages that can live there for several years. Lymphocytes are responsible for long-term immunity and can survive from a few weeks to decades. They are continually recycled from the blood to tissue fluids to lymph, and then back to the blood. (16)

Platelets develop from hemocytoblasts in the bone marrow, which receive on their receptors the hormone thrombopoietin produced in the liver and kidneys. A large cell called a megakaryoblast is produced, which breaks into tiny fragments that enter the bloodstream. About 25 to 40% of these platelets are stored in the spleen and released as needed, while the rest circulate freely in the blood and live about 10 days. (17)

Blood and the Circulatory System

The marvelous cardiovascular system that carries blood to every cell of the body is comprised of about 60,000 miles of blood vessels. Every day about 2,000 gallons of blood flow through this system, the blood volume totaling 4 to 6 quarts comprised of the plasma, red blood cells, leucocytes, platelets, and dissolved proteins and nutrients that provide these 10 trillion cells all of the nutrition they need to flourish. (18) The blood system is tied to lymph circulation, which circulates a clear liquid that helps rid the body of toxins. The heart, lungs, arteries, veins, coronary, and portal vessels work together in a marvelous way to bring oxygenated blood to the cells, and remove carbon dioxide and toxins from them. Perhaps now we can see why the blood and its circulation throughout the body to nourish every cell are so essential to life, and why it was natural that God would use it to symbolize life itself: “For the life of the flesh is in the blood …” (Leviticus 17:11).

It is just as natural that God would also utilize spilled blood of bulls, goats, sheep, and certain birds as a type of the blood of Jesus Christ that was spilled for our sins (Hebrews 9:13-14), since the blood and circulatory systems of these creatures mirror closely those of humans. Thus we have the laws of the sin offering, trespass offering, burnt offering, and peace offering wherein the blood of these sacrifices was, for example, sprinkled seven times before the vail (sin offering; Leviticus 4:5-6, 17), sprinkled on the horns of the alter of sweet incense (sin offering; Exodus 30:10), sprinkled on the altar (trespass offering; Leviticus 7:2), sprinkled around and upon the altar (burnt offering; Exodus 29:16), poured out at the bottom of the altar (sin offering; Exodus 29:12), and placed on the tip of the right ear, the thumb, and the big toe, and sprinkled upon, Aaron and his sons (peace offering; Exodus 29:20-21; Leviticus 8:23-24, 30). (19)

The symbolism of these instructions for the offerings, and the meanings behind the daily sacrifices, new moon sacrifices, and other sacrifices is profound, most of it beyond our current understandings, but we can safely say that the blood, its use, and the disposition of the animals and birds pictures our slain and resurrected Lord and Savior (Hebrews 9:6-28). They also reveal much about Him and His relationship to us.

Other Matters of Blood

As valuable as the blood of animal sacrifices is to picture Jesus Christ’s sacrifice, it is never to be eaten. This directive is made clear in Genesis 9:4, Leviticus 3:17, 7:26-27, 17:10-14, and 19:26, Deuteronomy 12:16 and 23, and 15:23, Ezekiel 33:25, and Acts 17:20 and 29, and 21:25. This directive runs contrary to the use of blood in many cultures, especially with the Maasai of Tanzania who bleed cattle and mix the blood with milk. People of other countries make sausage, soups, and sauces from the blood of cattle, goats, sheep, pigs, or poultry. (20) These countries are on all continents, including many in Europe and Scandinavia. I remember my Norwegian grandmother preparing a sausage made from pig’s blood, rice, and a few other ingredients when I was young in southwestern Minnesota.

The taboo against consuming blood has a physical as well as a spiritual basis. While blood has a high level of iron from the hemoglobin it contains, as well as significant levels of all nutrients necessary for life, its effects on the body are not totally positive. Parasites and diseases can be passed on by its consumption, but the major barriers to its consumption are spiritual. God plainly commands it must not be eaten, not just as a symbolic prohibition but surely as an affront to the spiritual condition of the person. We may not understand what negative effects blood may produce within our bodies — the temple of God (I Corinthians 3:16-17) — even when originating with a clean animal, but we can be assured that God understands both the spiritual and physical implications of blood consumption, and for our health and protection prohibits its use.

Blood, or at least a similitude of it, has been used as a plague to punish people and nations for their sins. The most obvious example is the turning of the Nile River to blood before Israel left Egypt at the time of Moses (Exodus 7:20-21). The two witnesses also will have power to turn water to blood (Revelation 11:6). It is likely that this blood was not literal blood containing hemoglobin, but rather an overgrowth of a red-colored microorganism of some sort that produced toxic compounds which killed fish and other life in the water, and rendered it undrinkable. A similar condition might be the “red tide” that occasionally infects the waters of the Gulf Coast of the United States, and certain other coastal areas around the world under certain conditions. (21) The microorganisms produce toxic substances that can kill fish, and are irritating to swimmers. The sea becoming like the “blood of a dead man” (i.e., dark and viscous) may present a different case, since the second angel poured a vial into the sea, which resulted in the death of all sea creatures [living souls] (Revelation 16:3). The third angel followed by pouring his vial upon the rivers and fountains of water, which became blood (Revelation 16:4). Again, literal blood is not implied here, but a pollution of the water to make it reddish in color and toxic to life.

Note also the third part of the sea becoming blood in Revelation 8:8, which killed the sea life in the affected waters (verse 9). Such a catastrophe resulted from a great extraterrestrial body striking the sea and creating havoc, including perhaps adding toxic minerals and a resulting microbial flush as the ecological balance attempted to restore itself. (22)

Many scriptures mention objects having the red color of blood, such as heavenly bodies like the moon, which “became blood” (Revelation 6:12; Joel 2:31; Acts 2:20), the rivers and fountains of water that became like blood (Revelation 16:14, and grapes that gave juice like blood (Genesis 49:11; Deuteronomy 32:14).

Something More About Blood

There is surely much more to this mystery of blood being the life of men and other creatures. One place to look in attempting to solve this mystery may be to the pigment that gives blood its red color. This compound, already discussed, is hemoglobin, a porphyrin ring compound that has received considerable attention in research laboratories throughout the world.

Hemoglobin is comprised of various protein molecules surrounding a nucleus of a rigid prophin structure that has specific dimensions and orientation. (23) The center of the molecule contains iron, but when the molecule was first formed magnesium was present, later replaced by iron. It is uncanny that the chlorophyll structure, the green photosynthetic material in plants, is virtually identical to this heme structure, and it contains magnesium at its core. (24) Let us examine chlorophyll for a moment.

Chlorophyll, like heme, has four identical pyrrole structures surrounding the coordinated metal core atom. Besides this, it has a “tail” of sorts containing five “isoprene” units. In total, the tail has 20 carbon atoms. This rigid molecule is like the strings of a harp, complete with its “tail antenna” to capture light frequencies (energy) of the sun … not all of them that strike it, just those of particular wave lengths.(25) The remainder, including green, are reflected, which is why chlorophyll has a green color.

One might say that the rigid pyrrole units are a sounding board unto which the harp is fastened. Thus, the energy of the sun is harvested by this brilliantly unique compound and transferred to carbon compounds through a cascade of complex reactions, which involves the splitting of water into oxygen and hydrogen, and at the same time releasing particles of matter. energy is translated into matter; the unseen “spirit essence” of God’s universe is transmuted into the PHYSICAL world! This is happening all of the time right under our noses whenever green plants are photosynthesizing around us.

This is the reaction that makes life possible on planet earth, because all food crops depend upon it for their growth. These plants literally harvest the unseen energy of the sun and make it available as plant materials that can be consumed directly by people and animals to give and perpetuate life.

Genesis 1:29-30. “And God said, Behold, I have given you every herb bearing seed which is upon the face of all the earth, and every tree, in which is the fruit of a tree yielding seed; to you it shall be for meat [food]. And to every beast of the earth, and to every fowl of the air, and to every thing that creeps upon the earth, wherein there is life, I have given every green herb for meat [food]: and it was so.”

Now consider hemoglobin, a nearly identical molecule to chlorophyll, except the porphin nucleus is coordinated with iron rather than magnesium. Its structure absorbs frequencies as does chlorophyll, but different ones such that the greens are absorbed and the reds are reflected when the compound is oxygenated; when oxygen is released the compound turns bluish. The situation is little different than in the mineral world, where highly oxidized forms of iron, like hematite and limonite, are red and yellow, whereas the reduced forms of iron, common in low-oxygen environments, produce dark-colored minerals, typical of waterlogged soils and anaerobic situations.

The life is in the blood — and the oxygen-transporting hemoglobin in the red blood cells — while the blood itself, and all of the compounds and energy it contains, ultimately are derived from the sunlight harvesting activity of chlorophyll in green plants. Both heme and chlorophyll contain identical porphin structures, tuned differently by the metal (iron or magnesium) each contains. What is God telling us here? He is bringing unseen frequencies, sensed by our eyes as light, into physical forms as atoms and molecules that comprise us … and it is the blood circulating within this physical form of God’s image that gives and sustains life.

The Most Valuable Message of Blood

As we have seen, blood can picture many things — the likeness of a reddish moon, water, or even grape juice — and it serves as the sustainer of life within every creature that has it. Yet, the most valuable symbolism of blood is the atoning quality it possesses for sinners.

Hebrews 9:12, 14. “… neither by the blood of goats and calves, but by His own blood He entered in once into the holy place, having obtained eternal redemption for us …. How much more shall the blood of Christ, who through the eternal spirit offered Himself without spot to God, purge your conscience from dead works to serve the living God.”

 Without forgiveness of sins we are dead. We appeal through Christ’s model prayer to ask for this forgiveness of sins (Matthew 6:12), which forgiveness removes our sins — our “missing the mark” — as far as the east is from the west (Psalm 103:12). The price that Jesus Christ paid for us through His shed blood more than covers our sins: it removes them! All though the New Testament we see the power of Christ’s blood …

… to remit sins and cleanse us (Mark 14:24; Luke 22:20; I John 1:7; Revelation 1:5-6).

… to purchase us from this world of corruption (Acts 20:28).

… to grant faith to us (Romans 3:24-25).

… to justify us in His sight (Romans 5:9).

… to give blessings in our lives (I Corinthians 10:16).

… to redeem us forever (Ephesians 1:7; Hebrews 9:12; I Peter 1:18-19; Revelation 5:9).

… to bring us near to the Father (Ephesians 2:13, 16).

… to make peace with Him, others, and ourselves (Colossians 1:14, 20).

… to clear our conscience from evil and serve the living God (Hebrews 9:12-14).

… to grant holiness to enter into His presence (Hebrews 10:19-20, 29).

… to sanctify us (Hebrews 13:12).

… to grant righteousness (Revelation 7:14).

… to overcome Satan the devil (Revelation 12:11).

Perhaps at no other time of the year than at Passover is the importance of the shed blood of Jesus Christ so deeply appreciated. “And almost all things are by the law purged with blood, and without shedding of blood is no remission” (Hebrews 9:22). The “law” referred to here is first of all the law of the offerings instituted at Mount Sinai, but since all of these physical laws and ordinances typify a higher spiritual reality, we know that the higher reality of these sacrifices is the sacrifice of Christ Himself. His spilled blood is typified by the blood of bulls, goats, and sheep. It is His purity and goodness that characterizes the spring feasts, a life that we ought to live every day of the year, for each day had a morning and evening sacrifice. His blood was shed for every day, and for all time.

Romans 11:33-34. “O the depths of the riches both of the wisdom and knowledge of God; how unsearchable are His judgements, and His ways past finding out! For who has known the mind of the Lord, or who has been His counselor?”

We have surely just touched the surface of understanding the importance of blood. Yet, we have a good start. We know that life is in the blood, and that the shed blood of Jesus Christ has been sacrificed for us. It has removed our sins. We are now free men! Let us internalize that truth fully and move forward to conquer the land of Canaan in our own lives, slaying the giants we face through His power, and walking across the parted Red Sea on dry land as the enemy’s forces are destroyed behind us!

Bibliography

  1. Most scriptural references are taken from the King James Version, with updated archaic language.
  2. J.R. Kohlenberger, III, The New Strong’s Expanded Exhaustive Concordance of the Bible, Thomas Nelson, Nashville, Tennessee, 2001.
  3. See reference 2.
  4. Blood function and composition, www.virtualmedicalcentre.com/anatomy/blood-function-and-composition/30.
  5. 5 to 17. See reference 4.
  1. Zimmerman, K., Circulatory System: Facts, function, and diseases, Live Science, http://www.livescience.com/22486-circulatory-system.html.
  2. Jukes, A., The Law of the Offerings, Kregel Publications, Grand Rapids, Michigan.
  3. Blood as food, http://en.wikipedia.org/wiki/ Blood_as_food.
  4. Red tide, http://en.wikipedia.org/wiki/ Red_tide.
  5. Syltie, P., The Three Edens, Xulon Press, Fairfax, Virginia, 2011.
  6. Hemoglobin, http://en.wikipedia.org/wiki/ Hemoglobin.
  7. Similarities between chlorophyll and hemoglobin, Allied Health Blog, http://alliedhealthblog.com/2010/11/the-similarities-between-chlorophyll-and-hemoglobin/
  8. Simpson, T., The dialectical laboratory; towards a re-thinking of the natural sciences, www.thomasksimpson.com/dialectical.html.