A Historical Note Concerning Salt in Vertebrate Blood and in the Sea

In 1902 and 1903 G. von Bunge and A. B. Macallum became impressed independently with the similarity between the salt content of ocean water and vertebrate blood. Von Bunge’s ideas concerned NaCl and were stated in a physiology text. Macallum’s ideas, related mostly to the proportions of Na, K, and Ca in sea water and blood, were set forth in a series of papers ending in 1926. Bayliss (1927) and Pearse and Gunter (1957) accepted this thesis. Conway (1943, 1945) questioned it on thegrounds that the salts from land erosion do not correspond to those in the sea. However, Rubey (1951) has shown that sea salt has come from the deep Earth rather than erosion. All ensuing discoveries have corresponded to that idea. As a side issue, the theory of the freshwater origin of fishes has succumbed to a large number of questioning papers. Now the von Bunge-Macallum theory is generally unquestioned. Some 8 1 years ago a German professor named Gustav von Bunge first sensed the importance of salt in the sea and in vertebrate blood, including the fluids of men and other mammals. He stated this idea in the fourth edition of his Lehrbuch der physiologischen und pathologischen chemie. The fourth edition of the physiological chemistry text by von Bunge was translated by Florence A. Sieveking Starling and edited by her famous husband and published in this country as a Textbook of Physiological and Pathological Chemistry by Bunge (1902), P. Blakiston’s Son and Co., Philadelphia. In England the same book was published by Kegan Paul. Presumably the fourth German edition was published in the same year, although I have not seen it. The attention of von Bunge seems to have been centered upon salt alone, which in the language of his day meant NaCl. Further developments led to more complicated ideas, but von Bunge’s thoughts seem to have been the beginning of the salinitypicture of bloodtoday as it involvesphysiology. Von Bunge drew many sentient conclusions about the kidneys, the blood of vertebrates, and the distribution of salts of the alkaline earth metals sodium and postassium. He pointed out that the carnivores and meat-eating men did not crave salt (NaCl) but that plant-eaters in animal populations and human society were always craving it. He said people probably overloaded their kidneys and caused nephritis by taking too much salt. This admonishment has a distinctly modern ring, but today the reasons are stated somewhat differently, although von Bunge may have been very close to correct for it is now known that the kidneys have as much to do with high blood pressure as the heart does, or more. Von Bunge called attention to the fact that vertebrate fluids are replete with NaC1, but plant tissues are potassium dominated. Thus the herbivores are always seeking salt (NaC1) for their blood and other fluids. Manuscript received April 28,1983;accepted May 12, 1983. Von Bunge said on page 101 of this treatise, “I am, however, convinced that the remarkably high percentage of salt in vertebrate animals, as well as the desire to take salt with our food, can only be satisfactorily explained by the theory of evolution.” That was a sharp insight due to his predilection for speculative thinking with the evidence available to him. He noted that most plants are rich in potassium and poor in sodium, except for marine species, and that the invertebrate land animals are similar to typical land plants in salt content. In summary, he said (p. 103), “These are facts which lead most readily to the interpretation that the vertebrates living on dry land originally came from the sea, and are still continuing to adapt themselves to their present surroundings, where they can get but little salt .” Von Bunge’s theory was a great leap forward and had great effect as the sudden truth always does. Von Bunge (1902) said that he was advancing his theory for the first time. There is a certain anomaly in the dating of von Bunge’s publications which I have not resolved at this writing. I have not seen a fourth German edition of his Lehrbuch, etc. of which the 1894 edition is said to be the “Dritte Aufl.” The situation is compounded by the listing of the American edition (P. Blakiston’s Son and Company) of the English edition as the “Second English Edition.” I know of no first Enghsh edition unless the London edition by Kegal Paul of the same date, a facsimile reproduction so far as I can see, is termed a first edition. This would be a bit odd and cavalier, but no more so than the English custom of ignoring hereditary titles such as the von of von Bunge, for everyone except the British. However, precise priority is not of deep importance and ideas may come from diverse workers at close periods or discoveries may come independently from various workers at closely related times. A. B. Macallum at Johns Hopkins University was led to somewhat similar conclusions as those of von Bunge by a different approach. He first considered the salt ions in marine medusae (1 903) and later considered the differences