Life at the Cell and Below-Cell Level. The Hidden History of a Fundamental Revolution in Biology
Gilbert N. Ling, Ph.D.
Pacific Press
ISBN 0-9707322-0-1

"Dr. Ling is one of the most inventive biochemist I have ever met."
Prof. Albert Szent-Györgyi,
Nobel Laureate

Chapter 5.

Evidence for the Cell Content as a Dilute Solution
(p. 26-28)

The basic tenet of the membrane theory that the cell interior consists of a dilute aqueous solution can be resolved into the tenet of free water and the tenet of free +since, as already mentioned, it was found at the turn of the century that K+ is the main intracellular cation of most living cells.73,75,98 pp 232-233 The experimental evidence for free water and free K+ came in the early 1930's and late 1940's, and thus years after alternative concepts of what one may loosely refer to as "bound water" and "bound K+" had already appeared (see Chapter 7). For this reason, I shall present only a brief sketch of the early evidence for free water and free K+ here, and delay their follow-ups until [10.2(3)] and [11.3(5)]after the opposing concepts have been reviewed.

5.1 Early evidence for free cell water

In 1930, A.V. Hill (1886-1977), Nobel Laureate, showed that urea distributes81 equally between muscle cell water and the surrounding medium. This led him to conclude that all water in living cells is free and none "bound" or "nonsolvent." Confirmations followed soon.82

5.2 Early evidence for free cell K+

In 1953, Professor Alan Hodgkin, Nobel Laureate and Professor Richard Keynes of the Cambridge University published their findings on the mobility of K+ in the giant nerve fiber (axon) of the cuttlefish.263 They concluded that K+ which enters an axon is found in the axoplasm in much the same state as in a 0.5 M KC1 solution.263 p 526 The importance accorded this piece of work could be seen from a passage written by another Nobel Laureate, Professor Bernard Katz in "Muscle, Nerve and Synapse."237

"Moreover, these authors (Ernst, Troshin and Ling) take the view that the potassium ions do not merely form counterions to the negatively charged colloidal structure but possess selective affinity and are chemically bound to the proteinates. {This sentence has not correctly represented my position. In my view, to be presented in Section [10.1(3)], cell K+ is adsorbed primarily by electrostatic forces and cannot be regarded as "chemically bound." Added by GL.} It seems, however, very difficult to support this view in the face of the following pertinent observations by Hodgkin and Keynes (1953) (Reference 263, added by GL}.... These results are discussed in detail because they are of crucial importance in the still persistent argument about the validity of the membrane concepts.... It was clear therefore that the labeled [K+, added by GL] ions that had entered the axoplasm continued, inside cells, to behave as free ions with approximately normal mobility."237 pp 42-44

Sixteen years after the publication of Hodgkin and Keynes' work summarized above, Kushmerick and Podolsky presented new findings in support of Hodgkin and Keynes' conclusion. Kushmerick and Podolsky measured the diffusion coefficients of seven labeled solutes in the cytoplasm of 3- to 6-mm-long frog muscle segments with open ends.264 The solutes were K+, Na+, Ca2+ (calcium ion), SO42- (sulfate ion), ATP (adenosine triphosphate), sucrose and sorbitol. They showed that all solutes (with the exception of Ca2+) demonstrated diffusion coefficients lower than their respective counterparts in free solution by a factor of two.


From these findings, they concluded that six of the solutes they studied, including K+ and ATP, exist in the free state in the cell water. And it was mechanical barriers inside the muscle cell, which caused the impartial two-fold reduction of their respective diffusion coefficients. Thus it would seem that Kushmerick and Podolsky had not only confirmed the free-cell-K+ tenet in particular but the broader free-cell-solute tenet of the membrane (pump) theory as well.


As mentioned above, further follow-ups for both the free K+ and free water ideas will not be presented until Chapters 10 and 11 respectively. Nonetheless, it may be pointed out here that all five investigators and reviewer cited above had overlooked some earlier relevant information in the literature.

In 1913, Rudolf Höber reported on the electrical conductance of frog muscle measured at a frequency (0.9 x 107 Hz), at which the membrane resistance is short-circuited and thus no longer interfering. Höber found the electrical conductance of muscle cytoplasm equal to that of a 0.1 to 0.2% NaCl solution.265 This finding contradicts the free K+ tenet of the membrane theory, according to which the measured conductance should equal or at least approximate that of an isotonic 0.7% NaCl solution in equilibrium with a normal frog muscle [4.1(2)]. Höber's finding has been confirmed repeatedly by other investigators including Professor A.V. Hillwhose work was mentioned aboveand myself.266; 15 Table 8.1

So far, we have focused on the membrane theory and its underlying assumption that living cells are membrane-enclosed dilute solutions. In what follows, I shall examine theories and facts more closely related to the concept that living cells are solid bodies of protoplasm. I shall begin with the emergence of a new branch of chemistry, called colloid chemistry.

"Life at the Cell and Below-Cell Level.
The Hidden History of a Fundamental Revolution in Biology":

Contents (PDF 218 Kb)
Preface (
PDF 155 Kb)
Answers to Reader's Queries (Read First!) (
PDF 120 Kb)

1. How It Began on the Wrong Foot---Perhaps Inescapably
2. The Same Mistake Repeated in Cell Physiology
3. How the Membrane Theory Began
4. Evidence for a Cell Membrane Covering All Living Cells
5. Evidence for the Cell Content as a Dilute Solution
6. Colloid, the Brain Child of a Chemist
7. Legacy of the Nearly Forgotten Pioneers
8. Aftermath of the Rout
9. Troshin's Sorption Theory for Solute Distribution
10. Ling's Fixed Charge Hypothesis (LFCH)
11. The Polarized Multilayer Theory of Cell Water
12. The Membrane-Pump Theory and Grave Contradictions
13. The Physico-chemical Makeup of the Cell Membrane
14. The Living State: Electronic Mechanisms for its Maintenance and Control
15. Physiological Activities: Electronic Mechanisms and Their Control by ATP, Drugs, Hormones and Other Cardinal Adsorbents
16. Summary Plus
17. Epilogue 

A Super-Glossary
List of Abbreviations
List of Figures, Tables and Equations
References (
PDF 193 Kb)
Subject Index
About the Author

"Life at the Cell and Below-Cell Level..."
"Gilbert Ling"